
























































































































































































































































































































































































































































































































































Class. T K\a55Q 
Book .V-i *' A_ 



COPYRIGHT DEPOSIT. 




































RADIO for EVERYBODY 










K 


























Radio 

•V I 

for 

Everybody 


Being a popular guide to practical radio¬ 
phone reception and transmission and !o the 
dot-and-dash reception and transmission 
of the radio telegraph, for the layman 
who wants to apply radio for his pleasure 
and profit without going in'o the special 
theories and the intricacies of the art. 


<y' 


y 


3/ 


By AUSTIN Cl LESCARBOURA 

J \\ 

Managing Editor, Scientific American 


Revised and Enlarged Edition 

A * 

) > 3 
> > 


SCIENTIFIC AMERICAN PUBLISHING COMPANY 

MUNN & COMPANY 
New York 
1923 







Copyright 1922 , 1923 
By 

Scientific American Publishing Co. 


All Rights Reserved 


The right of translation into all languages, 
including the Scandinavian, is reserved. 


Printed in the United States of America 
by the Andrew H. Kellogg Co., New York 


m 17 1923 


Cl A698657 


a, 




PREFACE 


T HIS little volume has grown up with radio 
telephone broadcasting. It was first con¬ 
ceived during the closing days of 1921, when one 
of the editors of the SCIENTIFIC American was 
invited to speak for the small radio audience 
then served by the only radio broadcasting sta¬ 
tion in the New York City district. It did not 
require unusual foresight or much stretching of 
the imagination to visualize what the future of 
this remarkable means of disseminating news, 
talks and music, would be, and accordingly the 
editorial staff of our journal decided then and 
there to devote considerable time and thought 
to radio. 

An old-time wireless amateur, it became my 
lot to pick up the thread of wireless or radio 
from where I had left off back in 1911, when the 
vacuum tube was just beginning to be talked 
about, and a few of the more fortunate amateurs 
boasted of their possession of these wonderful 
electric lamps. The task was far from an un- 


IV. 


PREFACE 


pleasant one. I spent some time studying the 
reaction of the general public to radio, following 
the inauguration of the broadcasting service in 
various sections of the country. I installed a 
radio receiving set in order to study this new art 
and its practical application at first hand. 
Indeed, the manuscript for the first edition of 
this book was written on the very table on which 
I have my radio receiving set; and as urgent as 
this work was in order to have it appear within 
the shortest possible time to be of the greatest 
service to the public, I am free to confess that 
I was often unable to resist the temptation of 
donning the head-phones and listen-in on the 
radio concerts at odd moments. 

Then, too, the hundreds and the thousands of 
inquiries which have poured into the editorial 
rooms of the SCIENTIFIC AMERICAN have been 
an invaluable guide, not to forget the numerous 
conversations with persons met in and out of 
business. And even with the considerable 
amount of editorial space which has been de¬ 
voted to radio developments in the SCIENTIFIC 
American during the development of popu¬ 
larized radio, it has been found utterly impos¬ 
sible to keep up with the demand for radio 


PREFACE 


v. 


information. We have covered only the out¬ 
standing features in our columns, having no 
space for details and working data. Hence the 
overflow of radio material has been diverted to 
this little book wherein it can be treated at length 
without regard to space restrictions. 

The first edition of this work bore the date 
of April ioth, 1922. It was soon exhausted, and 
several subsequent reprintings were necessary to 
supply the demand. But during the months 
which followed the appearance of the several 
editions, many developments took place in radio. 
As might well be expected, an art so young and 
so intricate as radio broadcasting was replete 
with rough spots, so to speak, which had to be 
removed or polished as time went on. Then, too, 
highly inventive minds have been at work in the 
radio field, and numerous new laboratory ideas 
of yesterday have reached the commercial, every¬ 
day application of the present. Therefore, much 
of the material which appeared in the early 
editions of this work has become obsolete—obso¬ 
lete in the short span of less than one year! No 
other art has shown such progress and so many 
and startling changes. 

So “Radio for Everybody,” begun with the 



VI. 


PREFACE 


birth of radio broadcasting, has grown right 
along. This edition has not only been fully re¬ 
vised, but more pages have been added to accom¬ 
modate the latest developments in the art. The 
last chapter contains all the outstanding develop¬ 
ments which have taken place since broadcasting 
was first introduced, while other chapters have 

been revised here and there to bring the text 

• 

down to the present day. 

Perhaps it is well here to repeat in part what 
I said in the preface to the previous editions: 
Radio broadcasting is and must remain a radio 
proposition. It calls for radio apparatus and 
some knowledge of radio communication as a 
whole, just as the owner of an automobile should 
have a general knowledge of the mechanism 
of the automobile, even though it is unnecessary 
to delve deeply into the minute construction of 
the machine and into the expansive field of auto¬ 
motive engineering. What is required is prac¬ 
tical and helpful information about the mechan¬ 
ism with which the results are obtained. 

This work has been written with that very 
thought in mind. It has been prepared for the 
layman who wants to enjoy radio concerts and 
talks to the utmost, but does not wish to take the 


PREFACE 


Vll. 


time and trouble to delve into the intricacies of 
radio engineering. It aims to give the essential, 
practical information, with a minimum of theory 
and the total absence of mathmetics. It should 
present much of interest to the beginner who is 
going to build or buy a radio set; it can teach 
not a few things to the radio devotee who pos¬ 
sesses a radio receiving set and wants to learn 
more about his set and better sets; it may pos¬ 
sibly have something of interest for the radio 
amateur who has progressed pretty far along in 
the art, although I am frank to say that for the 
dyed-in-the-wool radio amateur and radio engi¬ 
neer, this book is no doubt too elementary. 

I take this opportunity once more of thank¬ 
ing the radio fraternity as a. whole for its co¬ 
operation. Several of the leading radio manu¬ 
facturers have been more than kind in extending 
every possible facility to me in the preparation 
of the present revised edition. Then, too, I 
desire to thank the reader, whose very interest in 
radio has spurred me on to keep in touch with 
radio progress and, in that manner, partake of 
the pleasures of the most fascinating pastime of 
all ages. 

Finally, in reading the following pages of this 


Vlll. 


PREFACE 


little volume, friend reader, 1 do hope you will 
obtain as much enjoyment and knowledge from 
the practical application of the facts presented 
as I have gained in gathering the material and 
writing it for you. 


New York, 

March 15 th, 1923. 


The Author. 


CONTENTS 


CHAPTER I. 

The Elements of Radio Reception and Trans¬ 
mission . 1 

CHAPTER II. 

Radio-Phone Broadcasting—What it is and 

What it Means . 39 

CHAPTER III. 

Dot-and-Dash Broadcasting: From Market 

News to Time Signals. 73 

CHAPTER IV. 

Receiving Equipment and the Interception 

of Radio Waves. 93 

CHAPTER V. 

Operating the Radio Receiving Set and Mas¬ 
tering the Telegraph Code. 143 

CHAPTER VI. 

Making Big Sounds Out of Little Ones, or 

the Gentle Art of Amplifying. 177 

CHAPTER VII. 

Transmitting the Dot and Dashes of the 

Damped Radio Telegraph . 205 









X 


CONTENTS 


CHAPTER VIII. 

The Radio-Telephone Transmitter and C. W. 

Telegraph Transmitter . 229 

CHAPTER IX. 

The Unusual Uses of Radio on Land and Sea 

and in the Air. 247 

CHAPTER X. 

Radio in Working Clothes or the Application 

of Radio to Everyday Business. 259 

CHAPTER XI. 

How to Construct Simple Radio Receiving 

Sets for Radio-Phone Programs. 275 

CHAPTER XII. 

Later-Day Radio Developments and How to 

Apply Them to Broadcasting Reception. . 303 






Chapter I. 


THE ELEMENTS OF RADIO RECEP¬ 
TION AND TRANSMISSION 


A S far as nine persons out of every ten are concerned, 
the main interest in radio is to receive the radio¬ 
phone music and talks. Whether the receiving set is 
of the loose-coupled type or whether it employs the Arm¬ 
strong regenerative scheme makes little or no difference. 
These details are as so much Latin or Greek to the 
average person. The main object, after all, is to know 
just what kind of set is necessary, how simply it can be 
installed, and what it will cost. Otherwise stated, tlie 
average man is interested first and last in the performance 
and not in the thing itself. He wants to receive the 
radio-phone service without delving into the intricacies 
of radio—and we do not blame him. 

It should be that way. The radio-phone broadcasting 
service has given radio a popular mission to fulfill. It 
has brought radio out of the laboratory and commercial 
world and introduced it into the home circle, there to 
enlighten and to entertain as nothing else ever could. 
Formerly, radio was known and appreciated by the pub¬ 
lic at large in a very general and vague sort of way; but 
it was only on rare occasion that the average man came 
into intimate contact with radio. Certain persons who 
became interested in radio were mostly of that kind 
who delve deeply into intricate things and master numer¬ 
ous and difficult details. They have an engineering or 
even an experimental and inventive turn of mind. Such 



RADIO FOR EVERYBODY 


9 

/w 

persons no doubt care more about the arrangement and 
delicate manipulation of the components of their receiv¬ 
ing sets than they do about the kind of messages that are 
picked up. Listening to a radio-phone service, they are 
thinking all the while in terms of decrement and modula¬ 
tion and continuous wave transmitters, and in many in¬ 
stances they do not even know what has been said or 
played at the end of the performance! Their’s is a real 
interest in radio for the art’s sake, but they are decidedly 
in the minority. 

Today, be it remembered, the radio-phone service be¬ 
longs to everybody. It is intended for the public at 
large. And by the same token that branch of radio ac¬ 
tivity for which it stands must be kept devoid of techni¬ 
calities as far as possible if it is to expand and gain- still 
further favor. Devotees of the radio-phone look upon 
the broadcasting service just as they would the phono¬ 
graph. When they purchase a phonograph they do not 
have to learn how the records are made, what makes one 
record better than another, what the rate of vibration is 
for the various instruments recorded on a given record, 
what is the wave form of each instrument as impressed 
on the record, and so on. Their interest starts and ends 
with the desire to hear music. And, notwithstanding the 
intricacies of the radiophone, they look upon the radio¬ 
phone in exactly the same way. 

Radio Without A Struggle—Can it be Done? 

Let us have no illusions on the subject. Radio is a 
difficult and intricate branch of engineering; indeed, it 
represents the highest technique in applied electricity. 
Hence it becomes impossible to give real, helpful informa¬ 
tion on radio reception and transmission, yet steer clear 
of such formidable terms as variometers, condensers, 
regenerative circuits, logarithmic decrement, damped and 
continuous oscillations, and so on. However, it can all 
be explained in a simple and elementary way, and it must 
•be done. That, precisely, is the purpose of this book. 


RADIO FOR EVERYBODY 


Starting out with the very rudiments of the art, you, the 
reader, are to be introduced step by step to the various 
phases of the radio art until you have mastered the essen¬ 
tial elements of the subject. Then, should you desire to 
delve deeper into this most interesting of hobbies, you can 
readily turn to the more advanced works which are now 
available in large numbers. 

To begin with, radio communication, whether it be the 
radio-phone or the radiogram, is based on a cause and an 
effect, separated by a greater or less distance. The cause 
is the transmitter, which sets up certain disturbances or 
waves in space which travel in all directions until they 
reach the distant point and create the desired effect, 
which is the result obtained with the receiving set. 

In the instance of the radio-phone service, the cause 
is the radio-phone broadcasting station. There are a 
number of such stations located in various parts of the 
United States; indeed, virtually every section of the 
country is now served with music, news of the day, 
weather forecasts, crop and market reports, and so on. 
The radio-phone station sets up disturbances or waves in 
space which travel in all directions. These disturbances 
or waves may be intercepted at any point within the range 
of the station, and when so intercepted can be brought 
to suitable receiving instruments and reconverted into 
the original sounds of the music or talk, as the case may 
be, so as to give a faithful rendition to the radio audi¬ 
ence. That is the effect. 

, Now, just how the disturbances are set up and how 
they travel through space is still a problematical matter. 
Until Einstein came along and upset many of our pet 
theories with which we had explained so many things 
during several generations past, it was usually held that a 
radio transmitter set up vibrations or wave motions in 
ether. Ether is the name given to a hypothetical sub¬ 
stance held to exist everywhere, even in a vacuum. But 
with the ether explanation rendered more or less obso¬ 
lete by the said Einstein, as well as by certain astronomi- 


4 


RADIO FOR EVERYBODY 


cal experiments which have produced interesting and tell¬ 
ing results by way of confirming Einstein’s theories, our 
pet radio explanation has been rather shattered. 

Still, for all practical purposes we can state that cer¬ 
tain kinds of waves of an electromagnetic character are 
produced by a radio transmitter, and that these waves 
travel through space at 186,000 miles per second. These 
waves, too, have much the same characteristics as the 
waves which we call light, except as regards their wave 
length and as regards their frequency of vibration. 
Whereas the waves of visible light have a length to be 
measured in millionths of a millimeter, and a frequency 
of vibration of billions per second, the waves used in 
radio work are seldom less than 100 metres in length, and 
may be as long as 20,000 meters or more in the case of 
long-distance, high-power transmitters such as span the 
Atlantic. At the same time the frequency of radio waves 
is to be measured in millions down to thousands per sec¬ 
ond. These radio waves pass through space and pretty 
much through everything that stands in their way. They 
pass through stone walls, frame buildings, mountains, 
forests, and so on. Certain things, particularly masses 
of metal such as a huge steel structure, absorb a consid¬ 
erable volume of the radio waves, especially those of short 
wave length, but there is always a sufficient volume left 
to affect all receiving sets within range. 

The radio waves are everywhere, yet cannot be seen 
or felt. Without a receiving set it is impossible to tell 
if the air is permeated with radio traffic or whether it 
is absolutely barren. So far as is known, even the 
strongest radio waves have no direct effect on any of the 
five senses, which are the sole avenues whereby we ap¬ 
preciate anything that is external to ourselves. Directly, 
we cannot feel, hear, smell, taste or see the radio waves. 
While it is true that the eye is a detector of electro¬ 
magnetic waves such as light consists of, still, the unaided 
eye can only detect the very short waves of visible light 
which, as already mentioned, are minutely short and are 


RADIO FOR EVERYBODY 


5 


all contained within the narrow limits of a single octave; 
and while by means of certain luminous screens known 
as fluorescent screens the range of visibility can to some 
extent be increased, no such method will render visible 
even the shortest of the waves used in radio. 

Radio and the Pond of Still Water 

Other methods have had to be developed to detect 
radio waves. These methods intercept the radio waves 
and convert them into some form of energy which will 
come within the scope of our senses. The receiving set 
presents the usual means of converting radio waves into 
sound waves which affect the human ear. 

Now let us consider a pond of still water as space, 
in order to follow the formation and propagation of radio 
waves. When a pebble is thrown into the smooth water 
it starts a series of concentric ripples or waves, which 
spread out indefinitely with a speed of a few hundreths 
of a yard per second, Similarly, the electro-magnetic 
disturbance set up by a radio transmitter spreads out in 
all directions in ever increasing circles, at the astounding 
speed of 186,000 miles per second—virtually instantane¬ 
ous, in the practical sense. As the waves spread out 
over the pool, little bits of straw or grass may be seen 
to move as the waves reach them. These bits of straw 
or grass may be compared with the radio receiving sta¬ 
tions which are also affected as the radio waves reach 
them. 

It will be noted that the waves in the pond grow 
weaker as they extend farther and farther away from the 
point where the pebble was thrown into the water. The 
same thing occurs in radio; as the waves spread farther 
and farther away from the transmitter, they become 
weaker until they no longer have sufficient power to actu¬ 
ate a receiving set. Here, then, is an important point 
to bear in mind. The waves become weaker with dis¬ 
tance. Thus at a short distance from a powerful trans¬ 
mitter, a relatively crude receiving set can be employed to 


6 


RADIO FOR EVERYBODY 


detect the powerful waves. At a greater distance, the 
same relatively crude receiving set no longer responds to 
the attenuated waves. At a still greater distance the 
waves are so weak that they do not produce proper re¬ 
sponse in better receiving sets, and it becomes necessary 
to resort to some form of amplifying device for the pur¬ 
pose of building up the strength of the waves in order to 
obtain the proper degree of audibility. 

All of which indicates that the question of distance in 
radio communication is governed by several factors. Be¬ 
ginners in radio will insist on being informed how far 
this receiver will work and how far that transmitter can 
send, and they are always disappointed when told that 
questions such as these are not answerable. First of all, 
a receiving set cannot determine the distance over which 
it will receive. From a powerful transmitter it may re¬ 
ceive over a distance of 1,000 miles, but from a small 
amateur transmitter it may receive over a distance of only 
25 miles. It is the transmitter, then, that determines the 
receiving range. On the other hand, the transmitter may 
actuate a high-grade receiving set at a distance of 1,000 
miles, but a cheap set will not be actuated at a greater dis¬ 
tance than 100 miles. Again, atmospheric conditions have 
much to do with the range. Under ideal conditions the dis¬ 
tances covered may be three times the usual spans. Etence 
in all questions of receiving or transmitting ranges, it is 
necessary to take the receiving set, the transmitter, and 
the atmospheric conditions into consideration in order to 
obtain a satisfactory answer. There is no definite range 
for any given instrument; specific conditions at any given 
moment decide the range. Otherwise, all statements of 
ranges must be approximations of a very crude sort. 

The Important Question of Wave Length 

Returning to the pool of water, it will be noted that 
the waves in spreading out from the transmitter maintain 
a certain distance between themselves. If the distance 
from the crest of one wave to the crest of another is 

9 


RADIO FOR EVERYBODY 


7 


measured, we obtain the wave length, as in a—b in the 
accompanying sketch. In the case of the waves in water, 
the wave length is determined by the size of the stone, 
the wave length being greater when a larger stone is 
dropped into the water. In radio, however, the wave 
length has nothing to do with the size of the transmitter, 
although it is true that short wave lengths are employed 
for the smaller amateur transmitters, and longer wave 
lengths for the commercial stations, especially the huge 
transatlantic stations. While the waves are larger and 
therefore more powerful when a large transmitter is em¬ 
ployed, the wave length is determined by other factors 
as will be explained further on. 



What happens when a pebble and a large stone are dropped 
in still water. Note how the pebble causes small waves, and 
the large stone large waves. Measured from crest to crest, 
such as a—b, we obtain the wave length of the waves. 


The wave length determines the tuning of the trans¬ 
mitter and receiver alike. Tuning is such a confusing 
term to the layman, yet nothing could be simpler to 
understand. Tuning is nothing more than the adjusting 
of a receiver or transmitter to a given wave length, so 
that it will receive that wave length, in the case of the 
receiver, and transmit that wave length, in the case of 
the transmitter. Thus a transmitter is adjusted to> 






8 


RADIO FOR EVERYBODY 

200-meter wave length. The waves emitted by that trans¬ 
mitter are of 200 meters wave length. As they travel 
through space in all directions, they are intercepted by 
receiving sets. However, only those receiving sets that 
are tuned to 200-meter wave length receive the signals 
from the transmitter in question. Other receiving sets, 
tuned to a shorter or longer wave length, do not respond. 
On the other hand, if another transmitter is sending at 
the same time on a 600-meter wave length, then the 
first batch of receiving sets, adjusted to 200-meter wave 
length, will not respond to this second transmitter but 
will keep right on receiving from the 200-meter wave 
length transmitter. Other receivers, adjusted to the 600- 
meter wave length, will receive from the second trans¬ 
mitter, and so it goes. 

It is tuning that has made practical radio communi¬ 
cation possible. Were it not for tuned waves, it would 
be impossible for more than one transmitter to operate 
in a given area, for the simple reason that confusion 
would result if other transmitters operated at the same 
time. Now, with tuned waves, several transmitters can 
operate at the same time, and the receiving sets can be 
adjusted so that only the desired transmitters are inter¬ 
cepted and heard. Thus the radio broadcasting stations 
generally operate on 360-meter wave length. Amateur 
transmitters are by law limited to 200-meter wave length 
or less. Commercial stations operate on higher wave 
lengths. By dividing the wave 'length field into various 
classes, a minimum of interference results between trans¬ 
mitters. One can spend an entire evening listening to a 
radio-phone broadcasting station with hardly any inter¬ 
ference from radio /telegraph stations, thanks to the 360 
meter wave length reserved for radio-phone service. 

Another question which rather confuses the beginner 
in radio is whether there is a limit to the number of 
receiving stations that can listen in to a transmitter. As 
a matter of fact, there is no limit—at least in practice. 
Any number of receiving stations can be operating at the 


RADIO FOR EVERYBODY 


9 


same time, picking up the signals or music from one 
transmitter. Furthermore, the transmitting operator can¬ 
not tell how many receiving sets are listening to what he 
is sending. He simply sends, and there is no telling how 
- far his signals are going or how many persons are listen¬ 
ing in. 

Damped and Undamped Waves—Which? 

The waves dealt with so far in the pool of water are 
highly damped. Which means, in plain language, that 




The difference between damped or discontinuous waves, and 
undamped or continuous waves in water. Dropping a pebble 
into water causes damped waves, while using a paddle steadily 
produces continuous waves. 

they die down quickly. The pebble is dropped in the 
pool of water, and the waves created reach but a short 
distance away before they have virtually disappeared. 
In order to keep up a disturbance in the water, it is 
necessary to drop one pebble after another, so as to 
create a steady supply of waves, represented by groups or 
trains. Each group or train soon dies down, and is fol¬ 
lowed by the next one, and so on. 

In radio, we have the same condition when the usual 
spark transmitter is employed. The group or train of 
waves starts out strong but soon dies down, and a second 
train of waves must be started, onjy to die in the same 
manner. Such damped waves may be likened to the ac¬ 
tion of a pendulum. When the pendulum is given a 
push, it swings from side to side, but each swing is a 
trifle shorter than the preceding one, until the pendulum 
comes to a dead stop. Its action is damped, in other 


10 


RADIO FOR EVERYBODY 


words, and corresponds precisely to the action of damped 
radio transmitters. 

Of late years the undamped transmitter has gained 
much favor in radio. Lhilike the damped transmitter, 
the undamped type produces a steady flow of waves. 
There are no groups or trains. It is just as though a 
paddle were used in the pool of water, said paddle being 
worked back and forth so as to produce a steady series 
of waves, all of the same size and strength, with a 
uniform wave length maintained throughout. Or again, 
as though the pendulum were given a fresh push at each 
swing, so as to restore the initial energy, and in that 
manner it would not die down just so long as the energy 
was supplied. 

Undamped wave transmitters are employed in many 
commercial and amateur transmitters. They are also 
known as continuous wave transmitters or CW trans¬ 
mitters for short. Radio telephony is always carried on 
by means of a continuous wave or undamped wave trans¬ 
mitter. In the case of the undamped wave telegraph 
transmitter, the steady flow of waves is altered into short 
and long trains to represent the dots and dashes of the 
telegraph code. In the case of the radio telephone, how¬ 
ever, the steady supply of waves is modulated or varied 
by means of a telephone microphone, such as the trans¬ 
mitter of the usual telephone instrument, in order to 
impress the characteristics of music or speech on the con¬ 
tinuous waves. 

Electricity may he made to vibrate or oscillate and it is 
this vibration or oscillation that creates radio waves. Cur¬ 
rent from a storage battery or dry battery flows steadily 
and only in one direction. Current flows out of one ter¬ 
minal of the battery, through the circuit, and back to the 
other terminal of the battery. That is direct current. 
However, there is another form of current known as al¬ 
ternating current, which is generated by machines known 
as alternators, and by other methods. Alternating current 
does not flow steadily, nor does it maintain the same 


RADIO FOR EVERYBODY 


11 


direction of flow. At one instant 'the alternating current 
is flowing through the circuit in one direction, and the 
next instant it is flowing in the opposite direction, only 
to change back to the first direction the next msiant, and 
so on. Each complete change of direction is known as a 
cycle. Commercial alternating current, which is generally 
used for lighting and power purposes in most sections 
of the country today, is known as 60-cycle current; that 
is to say, it has gone through 60 cycles of change in one 
second, each cycle consisting of a rise in positive voltage 
from 0 to the maximum voltage and a fall to zero, and 
then a reversal with a negative rise in voltage from 0 
to the maximum voltage, and back to 0 again, and a 
repetition of the performance for the next cycle. 

Vibrating or oscillating currents of this kind are neces¬ 
sary to produce radio waves. However, the rate of vi¬ 
bration or oscillation, or the frequency, to use the radio 
term, must be of a much higher order than the 60-cycle 
frequency of lighting and power circuits. Thus the 200- 
meter wave length of the usual amateur transmitter repre¬ 
sents 1,500,000 cycles per second, while the 10,000-meter 
wave length of a highpower station- represents 30,000 
cycles per second. It will be noted that the frequency or 
number of cycles -per second determines the wave length. 
The frequency, on the other hand, in both the receiver 
and the transmitter is determined by two factors, known 
as inductance and capacity. 

'Inductance is the length of conductor in a circuit, so 
far as the layman is concerned, and we must keep to 
simple explanations in this work if we are to live up 
to its title. Thus if we have 100 feet of wire in a cir¬ 
cuit, we have four times as much inductance as in the 
same kind of wire 25 feet long. Inductance, for the sake 
of convenience, is generally arranged in the form of 
a spiral or a helix for the transmitter, using heavy 
conductor since the current being handled is rather a 
powerful one; for receiving purposes, on the other hand, 
the inductance is in the form of insulated wire wound 


12 


RADIO FOR EVERYBODY 


on tubes or wound in compact spools or coils for ready 
handling. 

The capacity is the ability of the circuit to store elec¬ 
tricity. Capacity is generally represented by a condenser, 
which is a reservoir or storage for electricity. In fact, 
the condenser is a real reservoir or storage for electricity. 
The storage battery is something entirely different, al¬ 
though it does serve to store electricity. It accomplishes 
this end by causing certain .chemical changes, and these 
chemical changes in turn generate electric current which 
may be drawn from the battery until it is restored to its 
original chemical condition, or completely discharged. 
Thus the current proper is not stored: it only serves to 
create certain chemical conditions. For most practical 
purposes, however, the storage battery is the only means 
available for storing ordinary current. 

The condenser is always made up of sheets of brass, 
aluminum, copper or tinfoil, separated by some non-con¬ 
ductor of electricity, referred to as the dielectric. A cer¬ 
tain number of metallic sheets are connected to one side of 
a circuit, while the same number of metallic sheets are con¬ 
nected to the other side. The non-conducting material or 
dielectric separates two sets of sheetst. Between the sheets 
of metal there is created a static pressure. This 
pressure accumulates or becomes greater until the con¬ 
denser, no longer capable of retaining the pressure, dis¬ 
charges the accumulated electricity back through the cir¬ 
cuit of which it forms part. The discharged current 
flows through the circuit from one set of plates to the 
other, and recharges the condenser with the • opposite 
polarity. No sooner is the recharging accomplished, 
when the condenser discharges again, this time in the 
opposite or original direction, of course, and so it goes, 
until the charge, getting weaker with each discharge, is 
entirely spent. All this can take place in a fraction of a 
second. Thus the discharge from a condenser takes the 
form of a vibrating current or oscillating current, which 
is the basis of radio waves. 


RADIO FOR EVERYBODY 


13 


The Antenna or Aerial 

Let us return for a moment to our pond of still water. 
Instead of a pebble, let us use a hinged paddle which 
can be moved back and forth to create waves. This 
paddle then becomes the agency for transferring power to 
the pool, which is the medium for distributing the waves. 
In radio the energy for creating the waves is generated 
by the transmitter, and a system of elevated and insu¬ 
late wires, known as the aerial, serves to impart the 
energy or waves into space. An aerial or, as it is more 
popularly called in the case of the receiving end of radio, 
an antenna, is employed at the receiving end to inter¬ 
cept the waves and to bring the energy down to the 
receiving set. The receiving antenna may be likened to a 
hinged paddle at some remote point from the first paddle 
creating waves in water. The receiving paddle is pro¬ 
vided with a bell. As the waves travel over the pond 
and finally reach the receiving paddle, they cause the 
paddle to sway and this action, in turn, rings the bell. 
This action is precisely that of the receiving antenna and 
the actuating of the receiving set. 

Aside from the aerial or the antenna, a ground con¬ 
nection is required in radio communication. The ground 
side means a good connection with any object that runs 
into the ground, such as a water pipe or a gas pipe, or 
even some object which is eventually connected with the 
ground, such as steam-heating pipe. In the country, where 
such pipes are not available, a good ground may be secured 
by fastening a wire to a metallic bucket is-dropped into a 
well or other body of water, Again, an iron rod may be 
driven down into moist soil, or a large sheet of copper or 
galvanized iron may be buried in moist soil. However, 
the securing of a good ground, as well as the construc¬ 
tion of the aerial or antenna, is reserved for other chapters. 

In reality, the aerial and the ground form a con¬ 
denser. The aerial and the ground are the plates of the 
condenser, while the space between is the non-conductor or 
insulator or dielectric, whichever you wish to call it. To 


14 


RADIO FOR EVERYBODY 


create radio waves it is necessary to have two surfaces 
separated by a distance of from ten to several hundred 
feet and to create between them an electric pressure which 
changes its direction first toward one surface, then toward 
the other. In other words, we must have a condenser 
effect. The current must change direction several thou¬ 
sand times per second. The aerial and the ground af¬ 
ford just such an arrangement, and between these we 
create an electric pressure of from one to 20,000 volts 
by means of a suitable transmitting equipment, which 
starts waves radiating out in all directions. These pres¬ 
sure waves are, however, only part of a radio wave. 
From any wire in which current is flowing electro-mag¬ 
netic waves are radiated; therefore, radio waves are made 
up of both electro-magnetic, and pressure electro-static 
waves. The creation of these waves may be compared to 
the action of hurling the pebble into the pond of still 
water, as already explained. The amperes (the measure 
of current flow) put into the aerial corresponds to the 
size of the pebble, while the volts (the pressure or poten¬ 
tial of an electric current) are equivalent to the force 
with which the pebble is hurled. The larger the pebble 
and the greater the force behind it, the bigger the splash 
and the consequent waves. The more amperes of cur¬ 
rent flowing in the aerial circuit and the greater the 
pressure in volts between the aerial and the ground, the 
stronger the waves radiated and the farther they will 
travel. 


Elements of Radio Communication 

So far, so good. In order to make use of radio waves 
for the practical purposes of sending messages and then 
receiving them at a distant point, it is necessary: 

(a) To produce regular electrical disturbances in a 
circuit which starts the waves. These disturbances are 
electrical currents which reverse rapidly in direction, or 
vibrate, so to speak. In radio parlance this characteris¬ 
tic is known as oscillating, and we speak of transmitting 


RADIO FOR EVERYBODY 


15- 


circuits as oscillating circuits, and of transmitters as os¬ 
cillators. The rapidity of the reversal determines the 
wave length, as we have already learned. 

(b) To get the waves into surrounding space, through 
which they travel with great speed. This is done by 
means of the transmitting aerial, which will be described 
further on. 

(0 _ By means of these waves, to set up electric cur¬ 
rents in a receiving circuit at a distant station. The 
device which these waves strikes as they come in, and 
which turns them over to the receiving circuit, is called 
the receiving antenna or aerial. 

( d ) To change these currents so that they may be 
detected by suitable apparatus. The operator usually re¬ 
ceives the messages through sounds in a telephone re¬ 
ceiver. 

There are various ways in which radio waves may be 
set up. The simplest consists of a spark coil, such as 
the type employed in automobile ignition systems; a con¬ 
denser represented by the aerial and the ground, and a 
soark gap arranged as shown in the accompanying diagram. 
The spark coil has two windings, namely, a primary and a 
secondary. To the primary coil, which consists of a rela¬ 
tively small number of turns of wire wound about the 
iron core of the coil, are connected the battery supply¬ 
ing the initial current and the vibrator or interrupter, 
which breaks up the current flow from the battery. The 
secondary consists of a large number of turns of wire 
wound over the primary winding. In the nature of elec¬ 
trical things, when current is passed through the primary, 
a high voltage current is produced in the secondary wind¬ 
ing. The primary current may be only six volts, but 
the secondary winding produces perhaps 5 to 10,000 volts. 
This stepping up of the voltage is a necessary part of 
radio transmitting. Transformers are larger devices in¬ 
tended for stepping up the voltage of heavy currents. 

At any rate, high voltaee current is produced in the 
secondary winding. The interrupter causes the secondary 


RADIO FOR EVERYBODY 


16 

to flow first in one direction, and then in the other, as 
the primary current is interrupted. The secondary cur¬ 
rent, flowing- for a moment in one direction, charges the 
condenser, consisting of aerial and ground. However, 
the capacity of the condenser is limited, and when it is 
charged to overflowing, it releases its energy which jumps 
the spark gap in the form of a fat spark, only to pile 
up on the other side of the condenser. Again the con¬ 
denser is filled to overflowing, and it discharges once 
more, this 'time causing the current to flow in a direction 


Aerial 



as an inductance coil for tuning purposes. 

opposite to that of the first time, and again the condenser 
is charged. Thus the discharges take place back and 
forth, but far faster than it takes to explain their action 
here. Indeed, the discharges travel back and forth with 
the speed of light, but gradually diminish in strength until 















RADIO FOR EVERYBODY 


17 


the charge is exhausted. Every time the vibrator in the 
primary circuit makes or breaks the current in the prim¬ 
ary, one of these trains of alternating current or oscilla¬ 
tory current is started. Since they die down rapidly, 
they are known as damped oscillations. Each one of 
these trains produces a single tick in the distant receiving 
station telephone, and it is the rapidity with which these 
trains follow one another that characterizes the “spark” 
or sound of a transmitter. If we increase the capacity 
or the inductance in the transmitting circuit, we increase 
the wave length, just as the increasing of the length or 
the weight of the pendulum affects its rate of swing. 

In actual practice the transmitter is connected to the 
aerial and ground. The oscillations charge the aerial 
and the ground, which act just as a huge condenser, as 
already explained. The longer the aerial, the longer the 
wave length of the aerial by itself. This is known as its 
natural wave length, as distinguished from what its wave 
length may be raised to or lower to by external capacity 
and inductance. The waves travel out from the aerial 
through space, and through the ground to the various re¬ 
ceiving stations. 

These waves can be intercepted at any point within 
range of the transmitting station. Obviously, the waves 
become weaker as they travel out from the transmitter. 
A short distance away, the waves may be intercepted by 
an inexpensive and relatively crude receiving set, but at 
a greater distance, when the waves are considerably 
weaker, a more elaborate and more sensitive receiving set 
must be employed. 

For receiving the waves, an antenna and a ground con¬ 
nection are necessary. The first step is to tune the an¬ 
tenna-ground circuit so as to bring it into harmony or 
resonance with the desired waves. When this is done, 
the waves flow down from the antenna to the ground. 
They may be diverted into suitable receiving apparatus by 
the simple arrangement shown in the accompanying il- 
lustrAion. However, even when they are diverted in this 


18 


RADIO FOR EVERYBODY 


manner, they are of frequencies of the order of several 
thousand cycles, and will not produce any sounds in the 
usual telephone receiver because they are beyond the 
range of audibility. But remember, the waves are in 
trains or groups. By making use of a device that can 
convert these trains or groups into direct current—current 
flowing in only one direction, we secure a series of im¬ 
pulses flowing in one direction. The device which accom¬ 
plishes this purpose is known as the detector. The current 
flowing through the telephone receiver is smoothed out 
into single impulses of a frequency corresponding to the 



The essentials of receiving radio signals, comprising the an¬ 
tenna, inductance coil for tuning, crystal detector, telephones, 

and the ground. 

speed of the vibrator or current supply at the transmit¬ 
ting end. Thus the diaphragm of the telephone is actu¬ 
ated at an audible frequency. 

In the case of undamped waves, which are produced in 
a different manner and received by more elaborate re¬ 
ceiving equipment, it is also necessary to bring the inter¬ 
cepted waves down to audibility. In the reception of con¬ 
tinuous wave radio telephony, however, the waves are 
modulated or altered by the impressed telephonic char¬ 
acteristics, ai 1 while the receiver mav not make the actual 









RADIO FOR EVERYBODY 


19 


waves themselves audible because of their high frequen¬ 
cies, it does make audible the fluctuating potential of the 
waves and reproduces the sounds uttered at the trans¬ 
mitter. In other words, it does not concern itself with 
the carrier waves, but only with the sounds carried. 

Fitting the Radio Apparatus to the Task in Hand 

In entering upon radio as a hobby, the beginner is 
confronted with a question of choice of apparatus. Thus 
he can buy the parts and build his own receiving set and 
•transmitter; he can buy the separate pieces of apparatus. 



Diagrammatic explanation of why a detector detects radio 
waves. The high frequency current produced by the inter¬ 
cepted wave is shown in the upper half of the diagram, while 
the lower half shows how the detector, being a one-way 
conductor, only permits half the current to flow through, 
therefore making it a direct current, which affects the tele¬ 
phone reeiver. Certain factors cause the individual pulsations 
of a wave train or group to slur into one note in the tele¬ 
phone receiver. Therefore, there is one sound for each train 

or group of waves. 


all finished and ready to be connected with other instru¬ 
ments so as to form a complete set; or he can buy a com¬ 
plete receiving set and sending set, all wired, ready to be 
used. Latterly, because of the popular interest in radio, 
there have appeared various types of phonograph-like 
receiving sets, in which the radio mechanism is so simple 
that virtually no knowledge of radio is required. 

If the layman is only interested in receiving radio¬ 
phone service, and does not care to be troubled with even 




20 


RADIO FOR EVERYBODY 


an elementary knowledge of radio, then by all means the 
simplest type of apparatus is urged. In that event it is 
well to purchase a complete receiving set, already wired, 
as self-contained as possible, which only needs to be con¬ 
nected to the aerial and ground for immediate results. 

If the layman wishes to do a little experimenting and 
little by little master the details of radio communication, 
then it may be well for him to purchase separate radio 
units, each one finished but so arranged as to permit its 
use with other units for all kinds of purposes. 

Finally, if the layman wishes to build his own receiving 
set not only because of the experience gained but also 
on the grounds of economy, then the various parts can 



A simple receiving: set, consisting: of a variable inductance, a 
crystal detector, and a pair of telephones. Such a set will re¬ 
ceive radiophone concerts over 25 miles and perhaps more with 

good conditions obtaining. 

be purchased and assembled. Some manufacturers today 
offer all the parts for a complete receiving set, thus facili¬ 
tating work of this kind. 

For transmitting work, the same applies. However, it 
is well to say here that transmitting is something quite 
different from receiving. Anyone can receive, without 










RADIO FOR EVERYBODY 


21 


licenses or other formality; but one must obtain licenses 
for transmitting. The transmitting station must be 
licensed by the Department of Commerce, as explained in 
another chapter, and the operator of such a station must 
pass an examination in sending and receiving in order 
to obtain an'operator’s license, without which one is barred 
from transmitting work. So, all in all, the layman had 
best confine his efforts to receiving only until some subse¬ 
quent time when he can afford to put in the necessary 
time to master the various details of radio in order to 
pass the Government test and obtain his operator’s license. 

The growth of radio-phone broadcasting has created 
a demand for simple receiving sets with the minimum of 
controls and adjustments. Thus there have appeared re¬ 
ceiving sets made in the form of phonographs which repre¬ 
sent an effort to cater to the desires of persons who want 
,>the radio-phone service with all the radio left out, so 
to speak. These sets must be developed to a high state 
of perfection in short order, but for the present they 
must be looked upon as being somewhat premature at¬ 
tempts. In fact, much of the receiving apparatus which is 
now on the market is designed for radio communication 
work rather than for radio-phone broadcasting work, and 
this applies particularly to those sets making use of large 
horns for throwing the sound out into a room, in place 
of the head ’phones. The time must come when such 
sets will be designed with special attention given to the 
acoustical properties of the various components, just as 
the better types of phonographs have been consistently 
developed through unceasing experimentation and re¬ 
search until they have been taken out of the talking ma¬ 
chine class. 

For short ranges, inexpensive radio receiving sets can 
be obtained. There are sets selling as low as $15.00, 
which give passable results with the broadcasting station 
but ten miles or so away. For $25.00 there are several 
receiving sets available which give good reception of 
radio-phone service up to 25 miles or more. These sets 


22 


RADIO FOR EVERYBODY 



batteries for its operation. It must have a low-voltage 
battery, giving from 1^ to 6 volts, depending on the 
type employed, and a high-voltage battery giving from 
15 to 22 1 / 2 volts. 1 he low-voltage battery is known as 


are quite simple, having only one or two controls for 
varing the wave length, and a simple detector of the so- 
called crystal type. Such a detector, as will be explained 
further on in the chapter dealing with receiving appara¬ 
tus, requires no battery current. 

Stepping beyond the 25-mile range, we come to the bet¬ 
ter kinds of receiving sets with more elaborate tuning 
devices and the so-called vacuum tube detector. This 
detector, unlike the simple crystal detector,, requires two< 


The interchangeable panel idea is quite popular at present. Kach 
component of a receiving set is mounted on a standardized 
panel, and as many panels as are desired can be used at one 
time with or without cabinets. The idea is quite similar to the 
sectional bookcase, which grows with one’s needs. 






RADIO FOR EVERYBODY 


23 


A or filament battery, because it operates the filament just 
as in the case of an ordinary electric light, while the 
B battery or plate battery has to do with the intricate 
workings of the tube. In one type of receiving set sell¬ 
ing for $75.00, and quite effective for ranges up to 75 
miles, a special V / 2 -volt tube is employed which can be 
operated on a single dry cell. Otherwise, the usual vacuum 
tube requires a storage battery because it draws over 
one ampere of current at a voltage of 6. 

Passing on to ranges over 100 miles, a still better 
set is required. We now reach a point where radio 
begins to cost real money. Figuring on the basis of 
$1.00 per mile, which is the figure generally quoted by 
conservative radio men, we come to sets of elaborate 
design costing upwards of $100.00, with numerous ac¬ 
cessories bringing the total cost up to $200 and $300. 
These sets are generally used in connection with what is 
known as an amplifier, which is a device for building up 
the weak signals or music or talk. The amplifier may 
be obtained in the one-step, in the two-step, or in the 
three-step models. Generally, the two-step model is em¬ 
ployed, for the reason that it gives an amplification of 
several hundred times the original signal strength, and 
does not cause too many foreign noises. Amplifiers make 
use of vacuum tubes, which in general appearance are 
very much like the detector tubes. They differ only in 
the vacuum content of the tube. Since the amplifiers 
magnify all sounds and irregularities in a circuit of which 
they form part, it stands to reason that everything is 
amplified together. For this reason the amplifier should 
only be used when the signal strength is quite low and 
must be increased for proper reception. Furthermore, 
amplifiers must be used in connection with loud-speaking 
telephones. It is often necessary to use the usual two-step 
amplifier, and then a separate amplifier for the loud¬ 
speaker when extremely loud music or talk is required 
for a large hall. 

At this point it becomes necessary to study the various 


24 


RADIO FOR EVERYBODY 


terms encountered in radio work, as well as the accom¬ 
panying diagram giving the various symbols showing how 
the different pieces of apparatus are designated in the 
wiring diagrams that follow. The author had wished to 
avoid all wiring diagrams, but found that there was no 
other manner in which specific information concerning 
the arrangement of radio apparatus, could be given. 
Simple transmitting and receiving sets could be shown in 
more pictorial form, but when the more advanced equip¬ 
ment is to be shown we must resort to the conventional 
wiring diagrams. However, a little attention given to 
these symbols will enable even the layman to master the 
art of reading a radio wiring diagram, and he then be¬ 
comes competent to read any wiring diagram to hi§ very 
substantial benefit. 

The most common terms employed in everyday radio 
work are as follows: 

Aerial —One or more wires insulated from and sus¬ 
pended at a certain height above the ground and 
used to radiate energy in the form of electric-mag¬ 
netic waves produced by a transmitter. When used 
for receiving purposes, the correct name is antenna, 
though both terms are used interchangeably for 
either reception or transmission. 

Alternating Current , (Abbreviated A. C.)—An electrical 
current whose direction of flow is constantly chang¬ 
ing during a period of time. Thus, when we speak of 
a 60-cycle alternating current, we mean one that com¬ 
pletely reverses its direction of flow sixty times per 
second. Alternating current plays a prominent part 
in many phases of the radio art. 

Ammeter —An instrument used for measuring the flow 
of current in amperes through a given circuit. Ar 
ammeter is invariably connected in series with a 
given circuit, so that the current has to flow through 
it. Sometimes, the current is passed through a heavy 
conductor placed across the ammeter proper, such a 


Alternator 

Ammeter 

Aerial 

Arc 

Battery 


-J&- 

-®r 

T or t 


1 

L 


Bu 


zzer 


f 


Condenser —) |—or -GErj_ 
Variable Condenser 
Connection of wires 

No connection 
Coupled coils 
Variable coupling 
Detector 
Gal variometer 
Gap.plain — 


G 

G 



+ 


Grid leak and 
Condenser 

Inductance 

Variable Inductance or 


jqp_ 


—'mim— 


K< 




i|i|i|i|i|i|i|i| — Resistance 


Variable resistance -'w^v- 


Single pole 

Owitones Single throw 

Single pole _^ 

Double throw 

Double pole ->■— 

)e throw 


Zimg 
Double pole 
Double throw 

Reversing 




Telephone Receiver^or<^) 
Telephone Transmitter z(J^ 


—(G)— Transformer <|J 


Vac 


uum 


Tubi 



Gap. guenched -llllll- 

Generator, D.C. 

Ground rrl T H 


Vo 


riom 


eter 



Voltmeter 




Standard symbols used in radio wiring: diagrams. These symbols 
should be mastered so that the radio devotee can understand wiring: 
diag:rams and follow out their instructions. 





















26 


RADIO FOR EVERYBODY 


conductor is known as a shunt, and permits of 
handling heavy currents. 

Ampere —The standard electrical unit of current flow. 

Amplifier —This term is used in referring to either an 
amplifier tube or an amplifier receiving unit. It is 
the device which builds up or magnifies the waves 
or sounds in a radio receiving set. (See vacuum 
tube.) 

Amplitude —In radio work, this refers to the highest 
point reached by a wave or oscillation, i. e., the crest 
of each wave. A wave may, therefore, have a high or 
low amplitude according to the initial energy which 
created it. 

Antenna —See aerial. 

Armstrong Circuit —See Regenerative Circuit. 

Atmospherics —Also known as static, strays, X’s. “The 
noises of space.” Natural electrical discharges oc¬ 
curring in the ether and in reality miniature lightning 
storms. Since these discharges travel through the 
same medium as radio waves, they are readily picked 
up by receivers and prove very troublesome at times. 
It is comparatively difficult to tune out these dis 
turbances for they have no definite wave length. 

Audio Frequencies —Frequencies corresponding to vibra¬ 
tions which are normally audible to the human ear. 
All frequencies below 10,000 cycles per second are 
termed audio frequencies. (See radio frequencies.) 

B Battery —The battery used for supplying the plate 
current for the vacuum tube. This battery generally 
runs from 15 volts to 22}T volts. 

Broadcasting —As applied to radio work, this stands for 
the simultaneous sending of intelligence either by 
radio telegraphy or telephony from a given central 
point for the benefit of a great number of receiving 
stations located within the broadcasting station’s 
range. 

Capacity, (abbreviated C)—Capacity as used in radio 
work plays a very important part. The unit of elec- 


RADIO FOR EVERYBODY 


27 


trical capacity is the Farad, but the farad being too 
large for practical radio work, the micro-farad (ab¬ 
breviated m. f. d.—one millionth of a farad) is used. 
Thus we speak of a receiving or transmitting con¬ 
denser having a capacity of .001 mfd, or one thou¬ 
sandth part of a microfarad. 

Cascade Amplification —This refers to high amplification 
of received radio signals, wherein several vacuum 
tubes are employed in cascade fashion which means 
that one amplifies the sounds or waves and passes 



Receiving: set of simple construction, mailing: use of a tuning: 
coil with single slider, a crystal detector, and a single telephone 
receiver. This set may be used lor short distances. 

them on to another, which amplifies the sounds and 
passes them on to another, and so on. Thus, we 
may speak of a three-step (cascade) amplifier. 
Choke Coil —A coil wound to have great self-induction or 
choking effect when in the path of alternating cur- 





28 


RADIO FOR EVERYBODY 


rent. Choking action when introduced in a radio cir¬ 
cuit is called impedance. 

Circuit —In radio and electrical work the path in which an 
electric current flows is called a circuit. A circuit 
may be open or closed or oscillating. 

Close Coupling —A tuning coil, set of coils, or a trans¬ 
former is said to be close-coupled when the primary 
and the secondary are very close together, thereby 
causing much mutual inductance, Coupling permits 
of the transference of energy from one circuit to an¬ 
other. Therefore, the closer the coupling, the greater 
the transference of energy and the interplay of the 
circuits. The primary of any coupler or transformer 
device is the winding which carries the initial cur¬ 
rent ; the secondary is the winding which receives its 
current from the primary. In a coupler the primary 
is connected to antenna and ground, and the second¬ 
ary is connected with the detector circuit. 

Condenser —Two or more sheets of metal separated by 
an insulator called the dielectric. A condenser is 
used in radio work for collecting electrical energy, 
and for bringing circuits into tune or resonance. 

Counterpoise —One or more wires stretched immediately 
above the earth, but insulated from the earth. The 
counterpoise wires are usually directly beneath the 
regular aerial. This device is employed in trans¬ 
mission and reception when a good ground connection 
is not available. The counterpoise is used nn aircraft 
radios, where a ground connection would be out of 
the question. It is also used extensively in continu¬ 
ous wave transmission. 

Continuous Wave, (Abbreviated C. W.)—A form of elec¬ 
tro-magnetic wave used extensively in radio work. 
C. W. waves have a constant amplitude and bv the 
same sign no damping effect, as distinguished from 
the older form of discontinuous waves which are soon 
damped out. C. W. makes possible long-distance 
amateur radio telegraphy, as well as radio telephony. 


RADIO FOR EVERYBODY 


29 


Coupler —A device for transferring radio energy from 
one circuit to another. Ordinarily, the primary 
winding of the coupler is connected with the antenna 



Receiving set made in the form of a phonograph; in fact; this 
cabinet may be used as a phonograph or radio telephone receiv¬ 
ing set at will. The radio set makes use of the phonograph horn. 


and ground, and the secondary with the detector 
circuit. Couplers are of several different types, such 
as the loose-coupler and vario-coupler. 

Crystal Detector —Certain metallic crystals when intro¬ 
duced in a radio receiving circuit have the property 
of rectifying the incoming signal oscillations, which 












30 


RADIO FOR EVERYBODY 


are high frequency alternating currents, into direct 
current, so that the resultant intermittent direct cur¬ 
rent will work a sensitive telephone receiver. 

Detector —Any apparatus which transforms the oscilla¬ 
tions received by the antenna into visible or audible 
indications. 

Direct Current, (abbreviated D. C.)—An electric current 
flowing continuously in one direction. In a two-wire 
circuit, for example, direct current always flows 
from the positive ^source to the negative return. 
Therefore, direct current always has a readily de¬ 
terminable polarity, while alternating current (A. C.), 
which is constantly reversing its polarity while flow¬ 
ing through a circuit, has no apparent polarity. 

Electron —The ultimate particle of negative electricity, 
which plays a fundamental part in the constitution 
of matter as well as in the electric current. Radio¬ 
active emanations, electric discharges, etc., consist of 
streams of electrons, ejected at immense velocities 
from the atoms of which they formed part; and 
ordinary electric currents are in some way an elec¬ 
tronic phenomenon. 

E. M. E .—Electromotive force or electrical pressure or 
potential, the unit of which is the volt. 

Ether —A hypothetical medium of great elasticity and 
extreme minuteness, supposed to pervade all space as 
well as the interior of solid bodies. It is the medium 
through which light, heat and radio waves have here¬ 
tofore been said to be transmitted. The Einstein 
theories have shattered the ether theory for the 
moment, however, although many radio men still cling 
to it in explaining radio transmission. 

Flat-Top Aerial — One whose suspended wires are 
stretched parallel to the earth. 

Frequency —In alternating currents, the rapid reversal of 
the current through a circuit. Thus, we speak of a 
60-cycle current as one which has sixty complete re¬ 
versals per second or a frequency of 60 cycles. (See 




A huge radio receiving get and loud-speaker, made in the form of a 
huge cabinet. Such a receiving set gives loud enough music to fill a 
large hall or motion picture theatre. 

































32 


RADIO FOR EVERYBODY 


Alternating Current and Audio and Radio Frequen¬ 
cies.) 

Grid Leak —A very high, non-inductive, resistance con¬ 
nected across the grid condenser or between the grid 
and the filament of a vacuum tube to permit exces¬ 
sive electrical charges to leak off to an external 
source, thus furnishing stable control under all opera¬ 
ting conditions. 

Ground, (or Earth which is the term used in England) — 
In radio work the ground is the other side of the 
wave distributing system. It functions in connection 
with the aerial or antenna of most sending and receiv¬ 
ing systems as a large condenser. The term “ground” 
is used for any connection with the earth, river or 
sea. (See counterpoise.) 

Harmonics —In radio, harmonics refer to the incidental 
waves mostly noticeable in undamped or C. W. wave 
operation. These harmonics differ in length and fre¬ 
quency to the true and original operative wave of 
such transmitters. The first harmonic is three times 
that of the true frequency, or one-third the wave 
length of the aerial; the second harmonic is five times 
the true frequency or one-fifth the wave length; the 
third harmonic is seven times the true frequency or 
one-seventh the wave length. At times, amateurs will 
hear the harmonics of high power long wave stations 
while their tuners are set for much shorter waves. 
This accounts for the reception of a radio-phone sta¬ 
tion at two entirely different points on the tuner of 
the receiving set. 

Henry —The unit of inductance. 

Hertzian Waves —‘Electro-magnetic waves named after 
the discoverer, Prof. Heinrich Hertz, in 1887. These 
waves are the basis of radio communication. 

Hook-up —A diagram showing the wiring of any wireless 
receiving or transmitting set. Diagrams of this kind 
make use of certain conventional symbols to repre¬ 
sent the various pieces of apparatus. 


RADIO FOR EVERYBODY 


33 


Hot Wire Ammeter —An instrument used in radio trans¬ 
mission work for measuring the current in amperes 
by means of a wire that expands in proportion to the 
heat generated by the current passing through it. 

Impedance —This is the term applied to the resistance 
offered by a coil of ware to a current flowing through 
it due to the counter-electromotive pressure, irre¬ 
spective of the actual resistance of the conductor in 
ohms. Counter-electromotive pressure is developed 
in certain forms of inductance, and this counteracts 
the flow of current to a greater or less degree. Irnpe- 
. dance may be said to be the result of reactance. 

Inductance, (abbreviated L)—Inductance, like capacity, 
plays a very prominent part in radio circuits. It is 
the transfer of an electric or magnetic current from 
an electrified or magnified body to a non-electrified 
or non-magnetized body by close proximity but with¬ 
out actual contact. The unit of inductance is the 
Henry. In radio work the mil-Henry and .the 
micro-Henry are the more practical terms used. 

Insulator —A non-conductive material through which 
electricity will not pass. 

Kilowatt, (abbreviated K. W.)—One thousand watts, a 
unit used in measuring large amounts of electricity. 

Loop Antenna —A small frame wound with a number of 
turns of wire used in reception and thus eliminating 
both outdoor antenna and ground connections. 

Loose-Coupler —(See Coupler.) 

Loud-speaker —Any receiving device designed to repro¬ 
duce signals or speech loud enough to be heard with¬ 
out the use of the conventional telephone receivers. 

Megohm —One million ohms. 

Microfarad, (abbreviated mfd.)—One millionth part of 
a Farad and the practical unit of capacity. 

Microphone —A device for converting sounds into elec¬ 
trical equivalents in a given circuit. In other words, 
the microphone transfers sounds to a given electrical 
circuit by causing certain variations in the flow of 


34 


RADIO FOR EVERYBODY 


electricity. It is the instrument used in both wire 
and radio telephony to transmit speech, and generally 
consists of a mass of loosely packed carbon grains 
held between carbon blocks, and subjected to vary¬ 
ing pressure by the vibration of the diaphragm. 

Milliampere, (abbreviated M. A.)—The thousandth part 
of one ampere. 

Natural Frequency —The natural wave length obtained 
with any aerial or circuit without the introduction 
of other elements. 

Ohm —The unit of electrical resistance. 

Ohm’s Law —The fundamental law of electricity. It states 
that the current in amperes flowing through a cir¬ 
cuit is equal to the pressure in volts divided by the 
resistance in Ohms. 

Oscillations —Alternating currents of very high frequen¬ 
cies are called electrical oscillations. If the amplitude 
of a series of oscillations is constant, the oscillations 
give rise to continuous or undamped waves; but if the 
amplitude is not constant and is of a decaying nature, 
as in the spark method of transmission, we obtain 
damped waves. 

Potential —Term applied to voltage or electrical pressure. 
(See EMF and Volt.) 

Radiation —The transmission of energy through space in 
the form of electro-magnetic waves. By the radiation 
of a transmitter is meant the volume of high fre¬ 
quency current which is being delivered to the aerial 
for propagation in the form of waves. 

Radio Frequencies —Frequencies corresponding to vibra¬ 
tions not normally audible to the human ear. All 
frequencies above 10,000 cycles per second are termed 
radio frequencies. (See Audio Frequencies.) 

Reactance —See Impedance. 

Rectifier —An apparatus which converts alternating cur¬ 
rent (A. C.) into pulses of direct current (D. C.) 
Tungar, Rectigon and Kenetron apparatus are em¬ 
ployed for rectifying purposes. Certain metallic 


RADIO FOR EVERYBODY 


35 


crystals also have rectifying action when used as de¬ 
tectors in reception. 

Regenerative Circuit, (also known as the Armstrong cir¬ 
cuit) a radio circuit comprising a vacuum tube so 
connected that after detection and rectification, the 
signal introduced in the plate circuit is led back to 
or caused to react upon the grid circuit, thereby in¬ 
creasing the original energy of the signal received by 
the grid and greatly amplifying the response to weak 
signals. In reception, the leading back or feeding 
back of plate energy to the grid for further strength¬ 
ening is usually accomplished by means of a small 
coil placed close to the secondary of the receiving 
tuner. This small coil is frequently called the 
“tickler.” 

Resistance —Opposition to the flow of an electric current 
through a conducting medium. All metals have more 
or less electrical resistance. Copper is used univer¬ 
sally for both electrical and radio work on account 
of its low resistance, comparatively low cost and 
ready supply. Silver is a better conductor, but it is 
too expensive. The unit of resistance is the Ohm. 

Resonance —A -very important function of radio circuits. 
Resonance in a given circuit is said to exist when 
its natural frequency has the same value as the fre¬ 
quency of the alternating electromotive force intro¬ 
duced in it. The current is then in tune with the 
natural period of vibration of the circuit. The 
theory of electrical resonance is the same as that of 
acoustics, readily demonstrated by the tuning forks, 
where one tuning fork will not respond to another 
unless it is of the same key or pitch. Bringing a cir¬ 
cuit into resonance means bringing it into tune with 
another circuit or transmitter. 

Rheostat —A variable resistance usually employed to con¬ 
trol or regulate current flow. 

Selectivity —In radio work, the ability to select any par- 


36 


RADIO FOR EVERYBODY 


ticular wave length to the exclusion of others; the 
fineness of tuning, in other words. 

Sharp Tuning —Where a very slight change of a tuner or 
tuning system will produce a marked effect in the 
strength of signals. The sharper the tuning, the 
greater the selectivity. 

Storage Battery —Battery which can be recharged at inter¬ 
vals whenever it is run down; a storage battery is 
employed to supply jcurrent for operating vacuum tube 
filaments. 

Static, (See Atmospherics)—Disturbances of an electrical 
nature which are created by natural causes and which 
interfere materially with radio work. When static 
is exceptionally bad it may be impossible to receive 
radio telegraph signals or radio-phone service through 
the heavy crashes and frying sound of the static. 

Transformer —Any device used in electrical and radio 
work for the transference of energy from one circuit 
to another, with or without a change in the voltage as 
desired. Thus we have Power Transformers, Am¬ 
plifying Transformers, Telephone Transformers, Os¬ 
cillation Transformers, Tuning Transformers, etc. 
All transformers have a primary and a secondary 
winding. The primary winding receives the initial 
current, which it passes on to the secondary winding, 
with the same voltage, a higher voltage, or a lower 
voltage, according to the ratio which the primary 
and secondary windings bear to one another. 

Tuning —The act of altering capacity or inductive values 
or both in a radio circuit so as to bring the circuit 
into resonance with an external source of similar 
character. In radio receiving, the greatest signal 
strength is possible only when the combined induc¬ 
tance and capacity values of the receiver match those 
of the transmitter. 

Undamped —A train of high frequency oscillations of 
constant amplitude such as continuous waves or C. W. 

Vacuum Tube, (abbreviated V. T.)—In radio work this 


RADIO FOR EVERYBODY 


37 


term is applied to a glass tube exhausted of air and 
containing essentially a filament for the creation of 
electrons; a plate, positively charged, to which the 
electrons are attracted ; and a grid, consisting of a 
helix of fine wire, inserted between the filament and 
the plate, for controlling the amount of electronic 
flow. This action of the vacuum tube plays three 
leading functions in radio work, namely, detection, 
amplification, and generation of high-frequency elec¬ 
tro-magnetic waves. 

Vario-Coupler —(See Coupler.) 

Variometer —An instrument which serves to vary the in¬ 
ductance and wave length value of any circuit in 
which it may be used. It consists of a set of fixed 
windings and a set of movable windings, the latter 
being rotated on twin axis in the usual construction. 
When both sets of coils carry the current flow in the 
same direction, the variometer has the maximum 
inductance value or wave length. When the coils 
are turned around so that the current flow in both 
sets of coils is in opposite directions, the coils are 
said to be “bucking” each other and the inductance 
and wave length value are at a minimum. 

Velocity of Waves —Radio, electricity and light waves 
travel through space at the speed of 186,000 miles 
per second, or 300,000 kilometers per second. 

Volt, (abbreviated V.)—The unit of electric pressure. 

Voltmeter —An instrument for measuring the voltage of 
a current flowing through an electric circuit. 

Watt, (abbreviated W.)—The unit of electric power. To 
find power in Watts multiply voltage by amperage. 
746 Watts equals one horsepower. 1,000 Watts 
equals one kilowatt (K. W.) 

Wave Length —Radio waves in their passage through the 
ether, travel in undulating wave form similar to the 
waves at a seashore. When the wind is blowing hard 
and steady the distance between each wave crest is 
comparatively long while if the wind is blowing more 


38 


RADIO FOR EVERYBODY 


mildly and in short spurts, the distance between wave 
crests is accordingly shorter and we have short waves. 
In radio, substitute the wind for the transmitter and 
you have the same action, so to speak. Wave length 
is, therefore, closely related to frequency,'?, c., long 
wave lengths have low natural frequencies while 
short wave lengths have greater natural frequencies. 
In general, short wave lengths are used for short 
distance low-power work, while long wave lengths are 
employed for long-distance, high-power work. 

The foregoing list by no means covers all the terms 
which will be encountered in radio, but it covers the 
more common and perhaps least understood terms con¬ 
fronting the layman at the very outset. As one gets along 
ever so little in the radio art, one accumulates a vocabu¬ 
lary of radio terms quite readily and with no effort. 

After all, radio is a subject which one soon masters. It 
is relatively simple after the essentials are clearly under¬ 
stood. Furthermore, in no other line of endeavor will 
one find so much good fellowship and so many oppor¬ 
tunities of receiving a helping hand. In all parts of the 
country there are radio amateurs who are ever ready to 
extend a helping hand to the novice, and one will do well 
to get in touch with the radio amateurs of the vicinity at 
the earliest possible moment. They are the greatest asset 
the novice has at his disposal. Furthermore, the radio 
and electrical dealers handling radio equipment are always 
ready to extend all possible co-operation and information 
to those in need of radio aid. It is part of their service; 
for, in purchasing radio apparatus, one is seeking a definite 
service rather than so much equipment. 

The reader is advised to keep in touch with radio devel¬ 
opments by reading the various periodicals devoted to the 
subject, as well as the radio sections of the various news¬ 
papers now paying special attention to the greatest hobby 
of the age. A real fund of valuable information can be 
picked up in this manner, especially after acquiring the 
very necessary fundamentals of the art, the imparting of 
which is the purpose of this book. 


Chapter II. 


RADIO-PHONE BROADCASTING— 
WHAT IT IS AND WHAT IT 

MEANS 


f f T ADIES and gentlemen, we take great pleasure in 
jL j introducing Mr. Percy Grainger, the famous 
pianist and composer, who will entertain us this evening 
with several of his favorite pianoforte selections. After 
that, please stand by until 9.55 for the re-transmission of 
the Arlington time signals -” 

A concert? No. A vaudeville performance? Hardly. 
A musicale in the home of a society leader? Not this 
time. 

It is merely a bit of radio-phone service taken at ran¬ 
dom. Another time it might be Mme. Lydi-a Lipkovska, 
court singer to the late Czar of Russia, or Miss Valentina 
Crispi, violinist, or Miss Sophie Tucker, famous delin¬ 
eator of darky and character songs. Again it might be 
Governor Edward I. Edwards of New Jersey, with his 
latest message, or Ed. Wynn and the entire company of 
“The Perfect Fool,” representing the first attempt to 
broadcast an entire theatrical performance; or Walter 
Camp, foremost authority in American athletics. 

The Radio Voice and its Audience 

Still again, at a different hour of the day, it may be 
the news of the moment, carefullv selected and clearly 
heralded word by word; marine news, weather reports, 
children’s bedtime stories, health talks, business talks, 



40 


RADIO FOR EVERYBODY 


fashion talks, agricultural reports, Babson’s statistical 
service, or the official time signals. For the radio-phone 
service is unlimited in its scope of subjects, just as it is 
virtually unlimited in the size of its audience. 

But what is the radio-phone service? Where is it 
obtainable, and how? What does it cost? Why is it free? 

Typical questions, these, at a time when radio is at the 
height of popularity. Only a short while back, the hobby 
of radio was indulged in by boys and voun? men, with 
occasionally a full-grown man, who, perhaps, were more 
fascinated by the technicalities of the radio art than by 
the actual feat of communication through space. Yet it 
is true that these enthusiasts, then as now, were carrying 
on radio conversations among themselves by means of 
the dot-and-dash language of the telegraph code; but it 
was certainly evident that they spent a goodly part of 
their time arranging and rearranging their radio trans¬ 
mitters and receivers in their insatiable ambition to span 
greater distances. 

Then came the radio-phone service, not as an occasional 
thing to startle the radio amateurs already engaged in 
sending and listening to the dot-dash messages, but as a 
regular established practice. A subsequent development 
brought about a definite operating schedule and a pre¬ 
determined program, so that now the person with a radio 
receiving set knows what is in store for him tonight, to¬ 
morrow night, or even next Sunday evening. Radio¬ 
phone programs are printed and mailed to persons on the 
mailing list of the various organizations doing this kind 
of work. 

In various cities throughout the country there are radio¬ 
phone broadcasting stations now in operation, which send 
out all kinds of information, talks, and music. With the 
proper type of receiving equipment it is now possible for 
any one to receive the radio-phone service from the nearest 
station, and, if there are several stations within receiving 
range, it is often possible to receive several radio-phone 
services, one by one, with absolute selectivity, although 
they may be operating simultaneously. That is to say, 


RADIO FOR EVERYBODY 


41 


with the apparatus properly tuned, one station may be 
heard; then, by slightly altering the tuning, another station 
may be picked up, and so on. Further tuning may pick 
up an amateur radio-phone transmitter or a commercial 



The radio-phone receiving: set finds a ready place in every pro¬ 
gressive home. Many an hour can be spent listening: to the 
musical programs, news of the day, weather forecasts, talks by 
prominent men, and other radio-phone broadcasting features. 


station operating or “talking” in the dot-dash-dot language 
of the Continental telegraph code, or again a powerful 
transatlantic station transmitting its messages at an ex¬ 
treme rate of speed, thanks to automatic transmitters at 










42 


RADIO FOR EVERYBODY 


one end and the photographic or phonographic recorders 
at the receiving end. 

Radio-phone broadcasting stations are sharply tuned; 
in fact, all radio-phone transmitters are sharply tuned; 
for, as we shall learn further on, this is one of the cardinal 
points in favor of the continuous wave transmitter, which 
is the basis of the radio-phone. Thus the utmost selec¬ 
tivity is obtained at the receiving end, and interference is 
reduced to a minimum. Indeed, the day is not far distant 
when a broadcasting station will be sending various serv¬ 
ices simultaneously, ranging all the way from a sermon 
to a jazz dance piece, and from a talk on economics to 
a fashion chat. The listener will merely have to tune hia 
or her receiver to any one of several wave lengths in 
order to obtain the desired service at that time. 

Back to the Humble Beginning 

There is no end of romance in the story of the radio¬ 
phone, radio telephone, or wireless telephone, whichever 
you please to call it. It is an invention that came back, 
so to speak, in a big way after an ignominious career. 
Such a wonderful thing—this idea of speaking through 
space without wires, cables, tubes or other physical con¬ 
nections—was almost certain to fall in the hands of un¬ 
scrupulous promoters, long before.the serious, honest ex¬ 
perimenters had had a-n opportunity of evolving something 
more than a crude, laboratory demonstration. So a dozen 
years ago we find the radio telephone nothing more than 
a crude device, making use of a sputtering, uncertain 
electric arc as the generator of the high-frequency energy. 
This high-frequency current, so uncertain as to be almost 
hopeless, was modulated or varied by means of some form 
of carbon microphone. This instrument, as any one 
familiar with its construction must know by now, is quite 
unsuited to the handling of heavy currents. It consists 
of little more than a mass of tiny carbon granules held 
between two carbon members. The passage of a heavy 
current through such a mass causes the carbon granules to 
fry or bake because of the heat developed through the 
imperfect contacts. 


* S’® 
















44 


RADIO FOR EVERYBODY 


It was the good fortune of the author to participate in 
wireless telephony back in 1908 and 1909, with a trans¬ 
mitter of the Telefunken type made in Germany. A series 
of experiments were being conducted for the United States 
Signal Corps, with a view to proving the practicability 
of radio telephony in military communication. The dis¬ 
tance to be spanned was some 18 miles, or the air line 
between Fort Hancock, Sandy Flook and Fort Wood, 
Bedloes Island, in the very shadow of the Statue of Lib¬ 
erty overlooking New York harbor. The high hills of 
Staten Island intervened, making communication between 
the two points all the more difficult. 

For the transmitter we were using ten electric arcs, 
arranged in series and supplied with a 550-volt direct 
current. Each arc consisted of a copper tank, filled with 
water, and a large carbon button. The ten arcs were 
arranged in two banks of five arcs each, and each bank was 
struck or started at the same time by pressing a single 
handle controlling five arcs at a time. Three sensitive 
ammeters indicated the state of each circuit—the input 
circuit, the closed oscillating circuit, and the antenna cir¬ 
cuit. The main object in this little game of wireless 
telephony was to get the three circuits, as reported by the 
meters, to behave—and what a job! No sooner was one 
circuit tamed, so to speak, so that the needle of its meter 
remained practically stationary, when attention would 
have to be given to the other two circuits whose meters 
were playing all kinds of antics. Then, at the moment 
when by mere chance all three meters were more or less 
steady, we were ready to talk. 

There was little to say, because if we were heard at the 
receiving end, it was more of a miracle than anything 
else. So we simply shouted numbers into the huge horn 
connected with the carbon microphone—“One. two, three, 
four,” and so on, followed by “Fort Wood. Fort Wood: 
how do you get me now? One, two, three, four.” and 
so on again, until the meters began their antics once more. 
Occasionally we played a phonograph, just as did so many 
other radio telephone workers in the pioneer days. 


RADIO FOR EVERYBODY 


45 


I he microphone was a renewable affair. The German 
builders of the apparatus, with all their characteristic 
thoroughness and fine workmanship, made the microphone 
in the form of simple cartridges which fitted into a holder 
at the small end of a long but narrow cardboard horn. 
Each microphone did not last much longer than five 
minutes after which it was little more than plain junk. 
While the author never knew the exact cost of these 
microphone cartridges, it is a. safe bet that they cost at 
least $2.00 each. Imagine wasting a $2.00 microphone 
for every five minutes of uncertain telephonic communi¬ 
cation ! 

Insurmountable Obstacles That Were Forgotten 

What of the results? Rotten, absolutely rotten! In 
all the long months of untiring efforts to work over the 
short eighteen-mile span between Fort Hancock and Fort 
Wood, the voice and the phonographic music only got 
through a half-dozen times, and then only for a few mo¬ 
ments so that odd bits of conversation or music were 
heard by the Signal Corps officers gathered at the receiv¬ 
ing end. 

There were many workers engaged in solving the wire¬ 
less telephone problem. Most of them used the arc gen¬ 
erator, following in the footsteps of the Danish scientist, 
Poulsen. Some used high-frequency alternators, but the 
design of these early machines was such as to give a low 
degree of efficiency. Nothing like reliable communication 
seemed possible, for the technical obstacles were far too 
g^eat and too numerous. 

But all the while certain stock promoters were reaping 
a harvest. To them, the wireless telephone presented an 
exceptional opportunity. The ever-credulous public liked 
the word pictures of the wireless telephone as painted by 
the clever stock salesman. The story of the Bell telephone 
was to be duplicated, but on a larger scale; wireless tele¬ 
phones were to be installed in every home; wires and 
cables were to be done away with; every one would carry 
a wireless telephone about in one’s vest pocket or hand- 


46 


RADIO FOR EVERYBODY 


bag, so as to ensure immediate communication with any 
one else, and so on. What a vivid picture, to be sure! 
Even at this late day, with the marvelous development that 
has taken place in wireless telephony, such a picture is 
quite out of keeping with what we can reasonably expect 
for decades to come. In fact, so long as the present sys¬ 
tem of wireless telephony is in force, it is doubtful if we 
can ever realize all the remarkable things that were prom¬ 
ised to the gullible stock purchasers of but a decade or 
more ago. 

Of course there were proofs. There had to be some¬ 
thing for the public to take interest in this latest scientific 
development, especially to the extent of parting with so 
much hard-earned money. Thus there was a demonstra¬ 
tion of the radio telephone between two of our cities. 
Everything worked to perfection. The results were abso¬ 
lutely wonderful. The public was enchanted, nothing less ; 
but the true scientists and radio workers were completely 
baffled. Then, when certain interests were closely inves¬ 
tigated, an unpaid bill for the leasing of a telegraph line 
between said two cities on a certain date, came to light. 
Needless to say, the date corresponded with that of the 
successful test of the wireless telephone. The inference 
is obvious. 

Another time, it was a German company’s turn to make 
a demonstration for the German army. The test was to 
be between Berlin and another city over one hundred miles 
away. Although nothing of much consequence had ever 
been done with this particular German wireless telephone 
system, on this occasion it worked like a charm. An in¬ 
quisitive German officer, seeking some explanation for the 
sudden upward jump in the radius covered by the wireless 
telephone, not to forget the remarkable clearness and loud¬ 
ness of the received conversation, suddenly discovered a 
telegraph line running direct between the transmitting 
station and the receiving station. There was no physical 
connection between the two, please be sure to note; but 
the transmitting aerial was parallel to and but a short 
distance away from the telegraph line at one end, while the 


At the transmitting end of the radio-phone broadcasting, showing how a singer and her accompanist are placed 
with relation to the special microphone transmitter. Successful broadcasting stations have spent a good deal of 
time studying microphones and acoustics in order to obtain the best results with their musical numbers 















48 


RADIO FOR EVERYBODY 


receiving antenna was parallel to and but a short distance 
away from the direct telegraph line at the other end. As 
far as wireless waves are concerned, there could be little 
gained by having a direct connection. It was scarcely 
more than straight wire telephony, except for the short 
jump at either end. In fact, this form of wireless tele¬ 
phony has, strangely enough, come to be used during the 
p%st year or two for transmitting telephone messages over 
high-power transmission lines. It is also used in wire 
work in a somewhat modified form, being known as “wired 
wireless,” as will be explained farther on. 

When a Rival Became a Partner 

And skipping over the numerous attempts to make 
something out of this remarkable laboratory toy, the wire¬ 
less telephone, we come to the time when the American 
Telephone and Telegraph Company took an interest in 
the vacuum tube perfected by Lee de Forest, as is explained 
elsewhere in this work. In the vacuum tube the telephone 
engineers realized that they had found a solution to many 
of their problems. The vacuum tube is nothing short of 
an electrical acrobat; it can do all sorts of tricks which 
no other electrical device has ever been able to perform. 
Thus it is a wonderful alternating current generator; feed 
it direct current and it gives forth alternating current of 
a wide range of frequencies. It is this characteristic which 
makes it available for wireless transmission purposes. 
Feed it alternating current, and it delivers direct current. 
This characteristic, just the reverse from the preceding 
one, makes it available as a rectifier for charging storage 
batteries, and, some day in the near future, as a substitute 
for the elaborate and costly rotary converter units now 
necessary in electrical transmission work, for converting 
alternating current used in high-voltage transmission, back 
into direct current of suitable voltage for commercial use. 
Feed it high-frequency alternating current, such as radio 
waves, and it converts them into audible pulsating currents 
which affect telephone receivers and thus are converted 
into audible sounds. That is how it is used as a detector. 


RADIO FOR EVERYBODY 


49 


Feed it ever so slight a fluctuating current, and it will con¬ 
trol or modulate or modify a far more powerful current; 
thus we have the weak current moulding a powerful cur¬ 
rent, and it is this feature which gives us the amplifier. 
It is this characteristic, too, that makes the vacuum tube 
the finest telephonic relay ever devised. It is used in long¬ 
distance telephone communication, so that the voice cur¬ 
rents, when greatly attenuated after traveling over hun¬ 
dreds of miles of wire, are brought to the grid member 



The farmer, using an inexpensive radio receiving set, can now 
keep in touch with the outside world. He hears the latest 
musical “hits,” and he receives weather forecasts, crop reports, 
and other information of real value. 


of the vacuum tube, and there serve to control a fresh 
and far more powerful current which starts off on the 
next lap of the journey, only to reach another vacuum 
tube when it in turn has become weak as a result of a long 
stretch. Again, the vacuum tube, because of its modu¬ 
lating characteristic, is the link between the carbon micro¬ 
phone or telephone transmitter of the ordinary kind, and 
the powerful currents of the radio telephone transmitter. 
At a stroke it eliminates all the troubles that seemed im- 







50 


RADIO FOR EVERYBODY 


possible of solution back in the early days of the wireless 
telephone. 

It was in 1915 that definite progress was first recorded 
in the history of the wireless telephone, for it was during 
the latter part of that year that the engineers of the Amer¬ 
ican Telephone and Telegraph Company succeeded in 
telephoning by wireless between Arlington, Va., and the 
Eiffd Tower, in Paris, or over a distance of three thou¬ 
sand miles. Over three hundred vacuum tubes were em¬ 
ployed to generate and modulate the high frequency cur¬ 
rent employed to span the Atlantic expanse. During the 
same tests the voice was carried through space all the way 
to Pearl Harbor, in the Hawaiian Islands, or a distance 
of almost five thousand miles. 

Do not forget that the stock promoters, back in the 
days when wireless telephony seemed so impossible to 
the really wise men, were telling us that the wireless tele¬ 
phone would be the great rival of the wire telephone. 
The wire telephone would certainly be put out of business 
in due course. Yet it was only when the engineers of the 
wire telephone came to take an interest in wireless tele¬ 
phony that this art made real progress. What is more, 
they developed wireless telephony to something practical; 
and the wireless telephone, in turn, gave wire telephony 
the vacuum tube and other valuable devices which made 
long-distance telephony practical. So instead of proving 
rivals, these two great means of communication have come 
to be partners, and always will remain partners. 

The Radf Link in Our Telephone System 

'Came the war, with still greater progress. Radio tele¬ 
phony on a small scale had to be perfected, because instant 
communication had to be made available between airplane 
units and the ground posts. When the United States 
entered the war, the best radio talent was put to work on 
this problem, with the result that the radio telephone in 
small units as well as large units, became a reality. Today 
it is possible to obtain a radio telephone of 5-watt rating- 
capable of transmitting over a distance of five to fifteen 

















RADIO FOR EVERYBODY 


v~> 

f > V 


WLEKLY PROGRAM 
RADIO-PHONE SERVICE 

WESTINGHOUSE ELECTRIC & Mfg Co. 
STATION W J Z. NEWARK. N. J. 

MON., DEC. 12th, TO SUN., DEC. 18th, 1921. 


This program can be heard by any one with 
suitable radio receiving apparatus within a radius 
of 100 miles of Newark. 

The service is absolutely free. 

Tune Instruments for 360-meter waves. 

REGULAR CONCERT 
DAILY, 8:20 to 9:25 P. M. 

MONDAY - - - Mme. May Peterson, Prima 
Donna Soprano, Opera Comique, Paris 

TUESDAY - - Os-Ke-Non-Ton, Indian Bar¬ 

itone: Messrs. Bertram Haigh and Ralph Brown, 
French horns; Miss Anita Wolf, Pianist 

WEDNESDAY-Mme. Gretchen Hood, Prima 
Donna Soprano, Theatre de la Monnai, Brussels 

THURSDAY - - Miss Helen Davis, Soprano; 
M. Cliff Young, Pianist 

FRIDAY - - - Westminister Orchestra 
SATURDAY - Dance music 

SUNDAY - - Miss Ethel Mackey, Soprano and 
Miss Mary Emerson, Pianist. Sacred Music 

OTHER FEATURES 

General News - - Newark Sunday Call News 
Service, daily, 7:55 P. M. 

Children’s Hour - - “Man-in-the-Moon” stories, 
by Miss Josephine Lawrence 
© Newark Sunday Call 

'Tuesday and Friday, 7:00 P. M. 
Hourly News Service - * Newark Sunday Call; 

weekdays, every hour 
from 11.00 A. M. to 
7:00 P. M. on the hour 

Radio Amateurs’ Night - - Thursday 7 P. M. 

J. B. WALKER editor Scientific American 
Weather Forecast (Official Gov’t) - - Daily, 

11:00 A. M., 5:00 and 10:03 P. M. 


Marine News - - Marine Engineering Service, 
weekdays (except Saturdays), 2:05 P. M. 
Official Arlington Time - * Daily, 9:55 P. M. 



(Program subject to change) 


One of the first programs of the radio¬ 
phone broadcasting service. Compare 
this program with one of the present 
programs reproduced on facing page. 


miles, as well as a 
500-watt transmitter 
capable of spanning 
500 miles or more. 
The war made radio 
telephony what it is: 
it was not an ill wind, 
for it blew some good. 

Today, the radio 
telephone is part and 
parcel of our wire 
telephone system, and 
it is fast becoming as 
practical in its true 
field as the latter. In¬ 
deed, were it not for 
the high cost of this 
form of communica¬ 
tion, it would be quite 
within the scope of 
present achievement 
for any telephone sub¬ 
scriber to call up a 
relative or friend on 
an ocean liner several 
hundred miles out at 
sea, the voice being 
carried over the usual 
telephone line to the 
central office, through 
trunk lines to the dis¬ 
tant radio transmitter, 
and thence transmitted 
through the air to the 
steamer. Two-way 
conversation could be 
effected, as with our 
usual telephone sys¬ 
tem. The radio link, 


















RADIO TELEPHONE 
BROADCASTING PROGRAM 

New York Cify District 

SUN., FEB. 12th, TO SUN., FEB. 19th, 1922 

li is program can be heard by any one with suitable radio receiving 

apparatus wuhin • radiu* of several hundred miles of New Ycrk 
I lie service Is absolutely free. Tune in struments for 300-meter waves. 

Sunday 

S P. M.—Radio-Chapel services, “The Spirit of 
Lincoln in a Radio-Unified World”, by Rev. 
Edgar Swan Wicrs, D.D., assisted by the quar¬ 
tette—Mrs. Wm. M. Rockwell, Mrs. M. S. 
Powell, Fred P. Taylor and George Roubaud; 
F. F. Iluxham, organist—from the Unitarian 
Church, Montclair, N. J. 

4 P. M.—“Abraham Lincoln”, an address by 
Rev. Robert Scott Inglis, of Newark, N. J. 

4.30 P. M.—“My Country Tis of Thee”, “Star 
Spangled Banner”; also several popular selections, 
including “Ty Tee”, “All That I Need Is You”; 
ployed by Paul Whiteman's Orchestra, from the 
Palais Royol, New York. Arranged through the 
courtesy of Leo Feist, Inc. 

7.00 P. M.—Sacred Music played by the Aeolian 
Orchestrelle. 

8.00 P. M.—“Listen to Me”, “Sweet Lady”, 
“Hawaiian Blues”, and several other selections 
from Carleton’s Tangerine, by members of the 
Tangerine Company, accompanied by the Casino 
Theatre Orchestra. Arranged through the cour¬ 
tesy of Leo Feist, Inc. 

Monday 

2.30 P. M:—-RayMiller’s Record Orchestra, assis¬ 
ted by Cliff “Ukelele Ike” Edwards. 

8.15 P. M.—Miss Ethel Grow, contralto, who ap¬ 
peared in English Opera and Concert, and in 
Oratorio in England, under the direction of Sir 
Henry Wood. 

8.45 P. M.—Gustav O. Homberger, cellist of the 
Kaltenborn String Quartette, who appeared in 
concert with the leading orchestras of Europe 
as solo cellist under Von Bulow, Rubinstein, 
Weingartner and Richard Strauss. Mr. Horn- 
berger will play a programme of selections by 
Goltermann, Chcpin, and Moskowski. 

Tuesday 

7 P.M.—“Man-in-the-Moon” stones for children. 

7.45 P. M.—“Tuberculosis, Influenza and Com¬ 
mon Colds”, a preventive lecture by Dr. Charles 
J. Hatfield, Managing Director of the National 
Tuberculosis Association. 

8.00 P M.—An address on radio by Paul F. 
Godley. 

8.20 P. M.—A second recital to the radio-phone 
audience by Mme. Gretchen Hood, Prima Donna 
Soprano, Theatre De La Monnair, Brussels; also 
of the San Carlo Opera Company, and prominent 
concert singer. Her program includes “Seger- 
bella” from Carmen, Bizet, and a group of bal¬ 
lads. Courtesy of Aeolian Company. 

8.45 P. M.—“Che Gelida Manina” from the Opera 
Boheme, Buccini, etc., by Charles Harrison, Tenor 
Soloist, Fifth Avenue Brick Presbyterian Church, 
for four years; studied with Frederick Bristol. 

9.20 P. M.—Songs and readings by Mr. and Mrs. 
E. E. Hofle, of Newark, N. J. 

Wednesday 

8.15 P. M.—Descriptive recital with music, of 
Verdi’s opera, "II Trovatore.” 

Thursday 

7.45 P. M —“Modern Health Problems”, an ad¬ 
dress by Dr. Royal S. Copeland, Commission¬ 
er of Health, New York City. 

8.00 P. M.—“What is a Rotary Club and What 
Are its Relations to the Public” by Allan Smith, 


THURSDAY ( continued ) 

Ex-President of the Newark Rotary-Club. Also 
a rotary song by Andrew Krenrich. 

8.20 P. M.— Classical music. 

9.20 P. M.—A program of songs by Janet Bush-. 
Hecbt, contralto soloist. First Congregational 
Church, Montclair, N. J., and a prize winner in a 
Newark Music Festival Contest. The program 
includes “In Flanders Fields”, “Would You,” 
“Bubbles”, and “Joyous Youth”, composition, 
of Mabelanna Corby, who will be the accompanist 
for these and other selections. Courtesy, Aeolian 
Company. 

Friday 

1.00—“Man-in-the-Moon” stories for children. 

8.15 P. M.—“Party Night,” when several well- 
known artists of vaudeville and the musical com¬ 
edy stage will entertain with songs and mono¬ 
logues. 

Saturday 

7.00 P. M.—Irv Pages Cornell Orchestra, Cornell 
University, composed of the following: Irv Page, 
banjo; Geo. Cox, banjo; Lyman Breese, banjo; 
Sam Bird, traps and drums; Jack Wallace, saxa- 
phone; and Paul Miller, cornet, banjo and violin. 

7.45 P. M.—“Fashion Talks to Women”, Mar¬ 
jorie Wells, N. Y. World. 

8.00 P. M.— The “Daily Dozen” exercises 
address, by Walter Camp, foremost authority in, 
American athletics. 

8.20 P. M.—Dance Music by the Fcrnwood Dance 
Orchestra of Newark, N. J. 

9.20 P. M.—Popular and character songs by 
Aileen Stanley, soprano, well-known in vaudeville 
circles. 

9.45 P. M.—“Hello Prosperity”, “Don’t Leave 
Me Mammy”, etc., by Max Hitrig, dramatic 
tenor, known from Coast to Coast. 

Duo Art Piano Recital. 

Sunday 

5 P. M.—Radio-Chapel Services, Rev. Clarence 
H. Wilson, D-D., Glen Ridge Congregational 
Church. 

4 P. M.—“Boys of the World”, an address by 
C. R. Scott, State Secretary of Boys’ Work, 
Y. M. C. A., Newark, N. J. Music by quartette 
Including Miss May Korb, soprano soloist, South 
Park Presbyterian Church; Miss Marian Adams, 
contralto soloist, Church of the Redeemer; Bruce 
Campbell, tenor, and Louis Burke, baritone, Clin¬ 
ton Avenue Reform Church. 

6 P. M.—Program of classical music by Mrs. 
Robt. Baldwin, violinist and Mrs. Ernest H. 
Harder, pianist. 

7.45 P. M.—Sacred Music'recital by the Aeolian 
Orchestrelle. 

8.00 P. M.—Ed Wynn and the entire company 
of “The Perfect Fool”, now playing at Geo. M. 
Cohan’s Theatre, New York. For the first time 
in the history of radio an attempt will be made to 
broadcast an entire theatrical performance. Ar¬ 
ranged by the N. Y. Globe. 

OTHER FEATURES 

Musical Program, weekdays, every hour from 11 a.irt. 
to 6 p. to . on the hour, 

“FASHION TALKS TO WOMEN", Marjorie Well*. N. Y. World 
Saturday 7.45 P. M. 

WEATHER FORECAST (Official) • Daily, 11:00 A. M.. 12,00. M 
5:00 and 10.01 P M. sharp. 

SHIPPING NEWS weekdays 2.05P. M. (excepting Sat.) by Marina 
Engineering and Shipping Age. 

BABSON’S Statistical Service. Monday, <J P. M. 

OKFICAL ARLINGTON TiME 9.52 P. M. 

AGRICULTURAL REPORTS. Official, daily 12.00 M„ and 8.00P.M 
“MAN-IN-THE-MOON” stories by Miss Josephine Lawrence 
< ©NewarkSunday Call). 

(Program will be announced, daily by radio phone 7-45 P. M.1 


A typical printed program of a single radio-phone broadcasting 
station. Such programs are mailed out to interested parties in 
order that one may know what to look for every evening of the 

forthcoming week. 






54 


RADIO FOR EVERYBODY 


as the radio telephone service is called when used in this 
manner, is destined to become commonplace within the 
next few years. 

Now the foregoing is no mere flight of fancy. It is a 
matter of record that the American Telephone and Tele¬ 
graph Company recently conducted a series of experiments 
with radio links and the trans-continental telephone line. 
Telephonic communication was established between the 
steamship “Gloucester,’’ cruising off Deal Beach, N. J., 
and Santa Catalina Island, situated some thirty miles off 
the California mainland in the vicinity of Long Beach. 
The telephonic communication, in this case, passed from 
the “Gloucester” to Deal Beach, N. J.; from Deal Beach 
to New York via telephone line; from New York to San 
Francisco via trans-continental telephone line; from San 
Francisco to Los Angeles via telephone line; from Los 
Angeles to Long Beach via telephone line; and from Long 
Beach by radio to Pebbly Beach, on Santa Catalina Island, 
and from Pebbly Beach to the Avalon exchange. From 
ocean to ocean via radio, telephone line, radio again and 
telephone line, through all the various circuits without 
appreciable distortion! 

't he first commercial radio and connecting land toll line 
is the Santa Catalina Island and California radio link, 
which was set in operation the latter part of 1920. Radio 
telephone service between Santa Catalina and the main¬ 
land to connect up with the Bell system exchanges was 
installed at the request of the local telephone company. 
Catalina is one of the great tourist resorts in California. 
It attracts thousands of visitors daily throughout the 
year, who, heretofore, when they left the California main¬ 
land, remained completely isolated from the rest of the 
world until they returned to the mainland, except for the 
much overloaded naval' radio telegraph station on the 
island. 

That this radio link, which bridges the 31*/2-mile gap 
between the island and the mainland, is not in the experi¬ 
mental stage may be gathered from the fact that it handles 
hundreds of messages each day. The large amount of 



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56 


RADIO FOR EVERYBODY 


commercial traffic with scarcely any interruption which 
the Avalon-Los Angeles toll circuit has carried since its 
inauguration is ample proof of the practicability of toll 
lines containing radio links, where, due to physical condi¬ 
tions, direct-wire connections are impracticable. 

It is virtually impossible to delve deeply into the intrica¬ 
cies of the Avalon-Los Angeles radio link and wire cir¬ 
cuit, since it involves the most elaborate telephone and 
radio engineering practice extant. Suffice it to state that 
the circuit consists of a little more than one mile of wire 
line from the Avalon central office to Pebbly Beach, a 
31^-mile radio link to Long Beach, and 25 miles addi¬ 
tional wire circuit to Los Angeles. This combination 
wire and radio circuit is operated as a unit, providing 
through telephone and signalling from Avalon to Los 
Angeles. At Avalon the circuit may be connected to any 
local subscriber’s line, and at Los Angeles to any local 
subscriber’s line, through local exchanges, or with other 
long-distance lines reaching practically any subscriber in 
the Bell system. 

The radio link is a duplex system: one message may 
be sent in each direction simultaneously. For transmit¬ 
ting, a fair-sized aerial is employed, while for receiving 
a loop antenna is used at each end. These loops are of 
the solenoidal or helical type, six feet square, and consist 
of only four or five turns each. To make the duplex 
operation a success, it goes almost without saying that 
exceptional measures had to be taken, otherwise the trans¬ 
mitter at one end would drown out the incoming signals 
on the loop antenna but a short distance away. The elimi¬ 
nation of such interference was attained by the use of 
different carrier frequencies for transmission in the two 
directions. 

Great things can be expected of the radio link. Whereas 
it would otherwise be necessary for a person, desiring 
to telephone by wireless, to have a radio telephone trans¬ 
mitter of his own or to visit a radio telephone station, it 
now becomes possible to employ a distant radio telephone 
transmitter through any Bell system telephone. It is only 



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58 


RADIO FOR EVERYBODY 


a matter of time when we shall talk over our telephone 
lines to our friends at sea, thanks to the radio link, 
although this service will always of necessity be expensive. 

How Radio-Phone Broadcasting Came About 

But the average reader of this book will no doubt be 
more interested in the radio-phone broadcasting develop¬ 
ment, which is a later-day phase. Before this broadcast¬ 
ing service became a regular thing, there were spasmodic 
efforts to send out musical programs, made by several 
radio companies, but these were intended rather as tests 
than as entertainment for tens of thousands of listeners. 
The present form of radio-phone broadcasting dates back 
to the latter part of 1920, when the Westinghouse Elec¬ 
tric and Manufacturing Company inaugurated the first 
radio-phone concert through its Pittsburgh station. Only 
a small number of persons heard the musical numbers 
sent out by KDKA, the Westinghouse station in Pitts¬ 
burgh. The phonograph was the only source of music, 
and the operator’s announcements sufficed for lectures 
and talks. The novelty of the feat was sufficient, of 
course, for the public had not yet been pampered, so to 
say. Problems arose over the manner and method of 
broadcasting, which had to be solved by experiment. 
There were many times during the first few weeks of 
broadcasting when the concerts were anything but pleasant 
to the ear. Then, as time passed on and through experi¬ 
ence the operators found out for themselves the kind of 
phonograph records which transmitted clearly and those 
which did not, what to avoid in the way of speech, what 
pleased the public and what raised its ire, and the various 
other little details which made or marred a radio perform¬ 
ance, the concerts began to pick up not a little. 

During this experimental stage letters began to trickle 
in from various parts of the country, telling of the re¬ 
ception of music and talks from KDKA. At first, returns 
were small, and mostly replies from established stations, 
which are always on the lookout for new developments 
m radio. These stations, by the way, lose no time in 


RADIO FOR EVERYBODY 


59 


corresponding with other stations they hear. After a 
time letters began to come from persons who had only 
recently purchased receiving sets, perhaps after hearing 
the concerts at one of the amateur stations. These lay¬ 
men increased in a steady stream and their number even 
at this writing increases steadily by leaps and bounds, 
Radio manufacturers are months behind in their produc¬ 
tion. 

Practically all the broadcasting by KDKA was pioneer¬ 
ing work. For instance, take the case of the radio church 
services. When the station was started, there was no 
program developed for Sunday evening. It was sug¬ 
gested that church services be tried. There was no prece¬ 
dent for this method of radio transmitting and conse¬ 
quently it was not known whether church services would 
broadcast well or, indeed, if the churches would consent 
to this method of handling their services. After some 
persuasion, however, permission was received from Cal¬ 
vary Episcopal Church of Pittsburgh, to broadcast its 
services. A district telephone line was installed between 
the church and the radio station for this purpose. 

Four microphones were installed in the church, to 
catch the voice of Edwin J. Van Etten, rector of the 
church, the choir, the chimes, and the organ, and the en¬ 
tire services were first sent out January 2nd, 1921. No 
one thing ever broadcasted by the radio station has been 
so popularly received. Letters poured in by the score to 
the Radio Division, telling of the pleasure and benefit of 
this new department in radio. Newspapers all over the 
country carried editorial announcements of the fact that 
church sermons were being broadcasted from Pittsburgh 
through the medium of the radio-phone. This was the 
first effort of its kind; and it made the radio-phone safe 
for the future. 

From Canned Music to the Real Thing 

After a time, when the church services were well known 
to all radio enthusiasts because of the clearness of trans¬ 
mission, the Westinghouse Company was requested by 


60 


RADIO FOR EVERYBODY 


members of the Herron Avenue Presbyterian Church to 
install a receiving- set and loud speaker to take the place 
of a long absent pastor. This was done, and the church 
assembled for an Episcopal service. But it listened to a 
sermon preached about fourteen miles away. This serv¬ 
ice, it goes without saying, was also a record, a milestone, 
if you please, since it was the first time two congrega¬ 
tions in separate churches had ever worshipped to one 
service, when a distance of miles separated them. It was 
also the first time that a metallic horn ever took the 
place of a flesh-and-blood minister. Again, this feat, al¬ 
most in the miracle class were it not for the fact that we 
have come to expect such marvelous things from modern 
science, attracted the attention of the press, with the result 
that more people than ever began to take an active inter¬ 
est in the radio telephone. 

In the meantime phonograph records comprised most 
of the evening musical programs. It was decided to do 
away as much as possible with the “canned” music and 
substitute real singers and musicians. Talent was not 
hard to obtain for this work, in most cases volunteering 
its services. Human voices began to come over the radio 
telephone instead of records, and were an agreeable change. 
Again an improvement was made in radio broadcasting— 
another milestone. Not satisfied with having merely local 
talent, the Radio Division of the Westinghouse organi¬ 
zation entered into an agreement with the managers of the 
local operatic concerts, with the result that when stars of 
the first magnitude came to Pittsburgh, their eflforts, vocal 
and instrumental, were and are being broadcasted over 
hundreds of miles. 

Not only in opera, but in the world of sport, the 
radio-phone service has been introduced. Casting about 
for features that would enliven the evening programs, it 
was decided to 'broadcast, as an experiment, blow-by-blow 
returns of a boxing match held in Pittsburgh. A private 
wire was installed from a boxing club to the radio sta¬ 
tion, and a man prominent in sporting circles engaged to 
render a round-by-round version of the progress of the 


RADIO FOR EVERYBODY 


61 


fight. So KDKA was the first broadcasting station ever 
to send out fight returns. Afterwards, the Dempsey- 
Carpentier bout in Jersey City, N. J., was broadcasted by 
a Radio Corporation station round by round. 

But operatic engagements and boxing bouts do not 
cover the entire gamut of public interest. So to the 
existing features there were added the news of the day, 
weather forecasts, agricultural reports, and other items of 
general interest, not to forget the occasional addresses 
by prominent men. 

In order to perfect the transmission of music and 
speeches by radio, the Westinghouse engineers have made 
considerable researches of the different frequencies of 
both. A studio has been built especially for the artists who 
sing, so that the radio-phone reproduction will be accur¬ 
ate. The studio in East Pittsburgh consists of a room 
20 by 30 feet, completely lined with burlap and devoid of 
windows, so that there will be no reflection of sounds. 
A report is made of every song, where the singer stands, 
how far away from the transmitters, and other incidental 
details. This report is checked up later with a receiving 
station and from this data considerable information has 
been obtained regarding the transmission of various kinds 
of music. This is only by way of showing how the new 
art has had to be developed, step by step. 

Extending the Broadcasting Area 

So successful did the East Pittsburgh radio-phone sta¬ 
tion prove and so great was the interest shown by the 
public and reflected by the unprecedented and even un¬ 
dreamed of demands for radio receiving equipment that 
the Westinghouse organization set to work opening up 
other broadcasting stations. At Newark, N. J., on the 
roof of the Company’s plant, there was installed a power¬ 
ful broadcasting transmitter known as WJZ. Down on 
the first floor of the building there is an attractive studio, 
equipped with various musical instruments and hung 
with curtains to make it sound-proof. In this studio ar¬ 
tists have been singing and playing, while speakers have 



Still another radio-phone broadcasting: station, showing: the announcer and the receiving: operators. This is 
of East Pittsburgh, Pa., the forerunner of all other radio-phone broadcasting stations in the United States. 

































RADIO FOR EVERYBODY 


63 


delivered their messages, for the benefit of the greatest 
audience ever gathered at one time. It is estimated that 
over 300,000 persons hear the concerts and talks broad¬ 
casted by the Newark radio-phone station, and that the 
effective area covered by this service takes in one-tenth 
of our total population. The service of this station can 
be heard by anyone within a radius of 100 miles of 
Newark, though as a matter of fact reports of the re¬ 
ception of the musical numbers and talks have come from 
Canada, Wisconsin, Florida, Cuba, and 600 miles out at 
sea. 

Then there is the Springfield station, known as WBZ, 
which supplies New England with the Westinghouse 
radio-phone service. Another station has been established 
in Chicago, known as KYW, and is intended for the 
Middle West and the Western States. 

Who Are the Broadcasters 

Organizations other than the Westinghouse company 
have not been slow to grasp the broadcasting idea and 
to enter the field. Thus by the end of 1922 there were 
close on to six hundred broadcasting stations in regular 
operation, covering every section of the country. Wyoming 
was the last State to have a broadcasting station. Cali¬ 
fornia leads in the number of broadcasting stations, with 
Ohio second and New York third. 

For the most part the broadcasting stations are owned 
and operated by concerns interested in the manufacture 
and sale of radio apparatus. Obviously, broadcasting is 
the very foundation upon which the bulk of the radio 
business now depends. Should broadcasting stop over¬ 
night, the radio industry in large measure would cease, 
for there would be little interest in listening to the dot- 
dash messages of commercial and amateur stations alike, 
so far as the general public is concerned. The radio 
companies, therefore, have gone into broadcasting for the 
sake of their business; with them it is just the reverse 
of the phonograph industry, which makes its profits on 
the sale of records rather than the sale of the machine. 


64 


RADIO FOR EVERYBODY 

% 


In radio the profit is made on the receiving apparatus, 
while the broadcasting service must be given away. 

Other interests have found it to their benefit to engage 
in broadcasting. Thus college, universities and schools 
have installed broadcasting stations and are giving regular 
programs for the entertainment and information of the 
public. Newspapers have established broadcasting sta-. 
tions, among the first to do so being the Detroit News, 
which operates that excellent broadcasting station known 
as WWJ. This example has been followed by the Atlantic 
Journal, the Kansas City Star, the Dallas News, and 
numerous others. It is part of a newspaper’s service to 
the public to give broadcasting programs and news. 

The General Electric Company have an excellent sta¬ 
tion, WGY, at Schenectady, N. Y., the range of which 
is considerably greater than that of most broadcasting 
stations. 

Then the Government has taken an interest in broad¬ 
casting. At least one Government station, which happens 
to be Naval Air Station radio telephone at Anacostia, 
D. C., sends out musical programs, and there can be no 
doubt that this station has been very popular with the 
radio listeners. The Post Office Department has a power¬ 
ful broadcasting station in Washington, D. C., which may 
be used for the dissemination of Governmental news and 
proclamations. 

Radio and the Department Stores 

Department stores have taken to broadcasting, not, as 
was originally expected, to disseminate the latest bargain 
counter news or to rhapsodize about the merits of their 
latest gowns or furniture or kitchen ware. Far from 
it! The department stores have been operating a broad¬ 
casting service of their own for some time past, sending 
out excellent musical programs and educational talks with¬ 
out a word of publicity. Thus there is the Bamberger 
store in Newark, N. J., which operates the WOR sta¬ 
tion. Starting with a DeForest transmitter of low power, 


RADIO FOR EVERYBODY 


65 


this department store has gone to a 500-watt Western 
Electric transmitter of great range, whiie their studio has 
been brought to a high state of development for the 
proper rendition of radio telephone music and talks. On 
one occasion, while Sir Thomas Lipton was visiting the 
United States, he spoke at the WOR station and his voice 
was heard by the Londoners in the Self ridge store, 3,000 
miles or more distant. 

Wanamaker, the large department store of New York 
and Philadelphia, maintains two broadcasting stations in 
those two cities. Gimbel has a radio telephone station 
in Philadelphia. Strawbridge and Clothier of Philadel¬ 
phia also have a broadcasting station. The Shepherd 
store of Boston has a powerful radio telephone which 
can be readily picked up several hunderd miles away. 
And there are numerous other department stores all over 
' the country which have installed broadcasting stations for 
the benefit of the community. 

Applying the Toll Scheme to Radio-phone 

Broadcasting 

Meanwhile the American Tel. & Tel. Company has 
installed a powerful radio telephone station on the roof 
of its 24-story building on Walker Street, New York. 
Steel tower.s 100 feet high serve to support the aerial. 
This station is unique in many respects. Designed and 
constructed by the engineers of the American Telephone 
and Telegraph Company and the Western Electric Com¬ 
pany, it was said to represent the last word in radio 
telephony. However, for some technical reason this sta¬ 
tion, located in the very heart of New York, has not 
proved satisfactory. Instead of using it for broadcasting, 
only the studio in the Walker street building has been em¬ 
ployed, and the modulated current is sent over telephone 
wires of the radio telephone station of the Western Elec¬ 
tric Company along the Hudson River frontage of New 
York City, known as station WEAF. 

The original plan of the telephone company has been 
to provide channels through which any one with whom 


66 


RADIO FOR EVERYBODY 


it makes a contract can send out his own programs, just 
as the company leases its long-distance telephone wire 
facilities for the use of newspapers, banks and other con¬ 
cerns. There have been many requests for such a service, 
not only from newspapers and entertainment agencies, but 
also from department stores and a great variety of bus¬ 
iness houses, according to the telephone officials. Obvi¬ 
ously, this is a simpler and more satisfactory way of 
solving the broadcasting problem than to keep on adding 
broadcasting stations each time one desires to transmit 
music or speeches or advertising talks. 

Up till the time these lines were written, the American 
Telephone and Telegraph Company has employed its 
powerful broadcasting station for the broadcasting of 
excellent musical programs and splendid talks. Publicity 
matter is being introduced now and then in an interesting 
and quite inoffensive manner and, indeed, it is not even 
noticeable, as a rule. 

The growth of the broadcasting stations has been both 
good and bad; good because it ensures something to listen 
to no matter where the receiving station may be located, 
and bad because too many stations only cause pandemo¬ 
nium to break loose. To make matters worse, the Gov¬ 
ernment has been very slow in passing suitable radio laws, 
with the result that all this while all radio telephones have 
been operating on the one and precisely same wave length, 
360 meters just as though there were no other available 
wave lengths. This has given rise to inexcusable inter¬ 
ference, just as many men engaged in a free-for-all shout¬ 
ing match in one room would make quite a racket. 

During the Fall of 1922 the Department of Commerce, 
which has charge of radio communications so far as 
Governmental regulation is concerned, introduced a special 
Class B designation for those radio-telephone broadcast¬ 
ing stations of great power, excellent rendition, and high 
grade musical programs. Stations enjoying the Class B 
rating are permitted to operate on 400-meter wave length, 
which makes them non-interfering with the usual broad- 


RADIO FOR EVERYBODY 


67 


casting stations operating on 360-meter wave length. The 
thought behind this new regulation is to create a group 
of powerful, well-managed stations throughout the country 
which can serve the largest number of listeners without 
interfering with other stations or being interfered with. 
Meanwhile, the smaller broadcasting stations can continue 
to operate, so that they have the same freedom as here- 
fore. Such stations are well adapted to local service, 
while the Class B stations are intended for nation-wide 
service. 

The Question of Dollars and Cents 

Broadcasting costs money. It is said that a single 
broadcasting station may cost in the neighborhood of 
$30,000 to $50,000 per year to operate. Of course, this 
means a broadcasting station giving high-grade musical 
programs. A small broadcasting station, making use of 
phonograph records and automatic piano a good part of 
the time, has a negligible operating cost. 

But where is the money to come from for this broad¬ 
casting activity? This question has been coming up over 
and over again ever since radio broadcasting began, and 
still there is no answer. Up till the present the broad¬ 
casters have found it worth their while if for nothing else 
than the creation of radio business. However, a time 
is coming soon when the radio business, while still thriv¬ 
ing, will not be as profitable as it has been, and the broad¬ 
casters will have to find a more direct and remunerative 
method of obtaining money for their activities. Again, 
until now the musical talent, the speakers and others who 
entertain the radio audience have offered their services 
without cost, either through purely unselfish motives or 
again for the publicity afforded. But now that radio has 
become commonplace and the romance is somewhat 
tarnished, the evil day will soon be upon us when musical 
entertainers, speakers and others will demand pay for 
appearing before the radio audience, just as they demand 
pay for any other public performance. 

So the problem of broadcasting must be solved sooner 
















RADIO FOR EVERYBODY 


69 


or later. The present situation constitutes a chimera, and 
is based on an uncertain foundation. Radio men and 
the public alike realize this state of affairs, and numerous 
ideas have been offered to solve the problem. 

Perhaps the most promising solution of the broadcast¬ 
ing problem is to form an association of radio manufac¬ 
turers, jobbers and dealers, and to assess each member a 
certain small percentage of his yearly turnover. The 
money thus raised can be turned over by the association 
to the broadcasters who, under the direction of the asso¬ 
ciation, will broadcast the most desirable kinds of pro¬ 
gram. Thus the broadcasters will have money to pay 
for the musicians and others, instead of having to depend 
on free services which are not always dependable. More 
than once we have heard a broadcasting station fill in its 
evening’s time allotment with phonograph or automatic 
piano selections, to cover over the failure of a performer 
to turn up. 

Another plan which has been suggested is to have the 
Government operate a group of radio telephone broadcast¬ 
ing stations and to tax the listeners or all the citizens in 
order to have funds available for operating the stations. 
These Government stations would operate irrespectively 
of other privately owned stations. Or again, the Gov¬ 
ernment might levy a special tax and turn over the pro¬ 
ceeds to the broadcasters. This is very much in line with 
the probable policy to be followed in Great Britain, where 
various plans have been considered for defraying broad¬ 
casting costs and finally the preference has been given 
to the tax plan, in principle in not yet in practice. 

Why Not More Quality and Less Quantity? 

However all that may he, it is certain that today there 
are too many broadcasting stations of the poorer variety. 
It would be far better to have less volume and better 
quality. Furthermore, all the money which is being ex¬ 
pended to maintain all these broadcasting stations, many 
of which can operate only a very small portion of each 
day and are therefore tieing up capital uselessly, might 


70 


RADIO FOR EVERYBODY 


better be concentrated and paid to operate a smaller num¬ 
ber of highest grade stations. Sooner or later this phase 
of the radio industry must crystallize and some equitable 
arrangement will be w r orked out for the good of the radio 
industry and the public alike. 

Meanwhile there is nothing more fascinating than listen¬ 
ing to the broadcasting stations, especially if one possesses 
a good receiving set which enables sharp tuning. One 
turns the various knobs of the tuner, and short and long 
buzzes are heard, following each other in a lazy sort of 
way, indicating that an amateur transmitter is at work. 
Again the tuning knobs are adjusted, and a peculiar 
whistling sound is detected. Finer adjustment of the 
tuner converts the whistle into music, followed by a voice 
which informs us as to whom we are listening. Further 
adjustment of the tuner brings in rapid dots and dashes 
of a ship at sea and the answering land station. With 
his hands on the tuning handles, the radio novice can pro¬ 
ject his ears to distant cities and ships at sea. And yet 
we have reflected over the thrills of the magic carpet 
which carried its owner to distant points at his mere 
wish! 

The quality of the radio-phone transmission has been 
steadily improved. In the beginning the musical rendition 
was of a low order, especially when an orchestral or band 
selection was being transmitted. The instruments would 
blast to such an extent that the music was no longer 
music, but simply plain noise. 

The problem of acoustics has received careful con¬ 
sideration on the part of the broadcasters. As a result, 
remarkable studios have been built, in which the walls 
and ceilings and other features are designed and con¬ 
structed with a view to minimum echo or sound reflections. 
Then, too, the electrical equipment has been studied and 
redesigned and reconstructed with a view to covering a 
larger range of sound frequencies. Today there are 
scores of radio telephone transmitters which broadcast 
delightful music with a minimum of distortion. Indeed, 


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72 


RADIO FOR EVERYBODY 


it is to be hoped that just as much care will be taken in 
the designing and construction of future receiving sets 
and loud-speakers as has been taken at the transmitting 
end, for the music can be no better than the poorest in¬ 
strument in the long chain of interconnected devices from 
the -microphone which catches the singer’s voice, to the 
modulator, radio-phone transmitter, the radio wave, the 
intercepting antenna, receiving set, amplifier, and last, 
but by no means least, the loud-speaker. 

The radio telephone is one of the greatest inventions of 
the age. It brings right into our homes the information 
we desire and the best of music. Not so long ago an 
entire musical comedy was broadcasted, and the listener 
could almost visualize the performance. Even the dances 
were broadcasted, the dancers wearing special wooden 
shoes so that the sounds of their prancing feet could be 
transmitted. Imagine what the radio broadcasting service 
means to the farmer, far removed from the city yet at 
last in daily touch with metropolitan life! To many city 
dwellers, too, the broadcasting service has brought a new 
and interesting addition to home life. 


Chapter ITT. 


DOT-AND-DASH BROADCASTING: 
FROM MARKET NEWS TO 
TIME SIGNALS 


T O the layman, of course, the radio-phone broadcast¬ 
ing is the only thing that counts. The dots and 
dashes that are picked up are meaningless. It may be 
interesting to note the different kinds of radio telegraph 
transmitters that can be picked out of the air; perhaps 
there is some interest in noting their relative strength: 
but from a truly practical standpoint, they have little 
value to the layman who has not as yet mastered the 
telegraph code. 

However, aside from the radio-phone broadcasting 
service, there is an excellent radio telegraph broadcasting 
service now available in practically every part of the 
United States. It is known as the radio market news 
service of the United States Bureau of Markets and Crop 
Estimates and represents an effort on the part of the 
Bureau to make its market news more immediately avail¬ 
able and more effective than it can be made in any other 
way. Ever since the inauguration of the first market news 
service on fruits and vegetables in May, 1915, the special¬ 
ists of the Bureau have given continuous study to the 
problem of supplying market news on agricultural com¬ 
modities to those who may have use for such information 
as quickly as possible after it can be obtained. The 
market news services of the Bureau cover live stock and 
meats; dairy and poultry products; fruits and vegetables; 


74 


RADIO FOR EVERYBODY 


hay, feed and seeds, and some other commodities asso¬ 
ciated with these four general groups. The information 
is supplied to and is utilized by producers, shippers, 
dealers, brokers and commission men, manufacturers, 
warehousemen, demonstration and extension workers, 
banks, transportation agencies, chamber of commerce, buy¬ 
ing and selling organizations, and other commercial, exten¬ 
sion and educational agencies. 

Getting the News to the Public 

It is the function of the Bureau of Markets and Crop 
Estimates to gather or assemble market information from 
reliable sources and distribute it in such a way as to make 
it available to the greatest possible number who wish to 
use it. In performing this function it utilizes and co¬ 
operates with all agencies possible. It affiliates with State 
agencies which may or may not have similar functions with 
respect to the State as the United States Bureau of Mar¬ 
kets and Crop Estimates has to the Federal Government. 
It utilizes the railroads for information relative to ship¬ 
ments and movements. In one way or another, it assem¬ 
bles information from every available source where such 
information can be obtained. 

In utilizing radio communication as a means of dis¬ 
seminating crop and market information, the Bureau of 
Markets and Crop Estimates -is taking advantage of one 
of the agencies which has certain possibilities possessed 
by none that has been used in the past. This new method 
makes it possible for all who wish this information to help 
themselves to it, if they will but equip themselves to 
receive it in the form in which it is sent. The advantages 
of broadcasting information by radio are (1) that the 
information can be intercepted or copied by means of suit¬ 
able equipment at any point within certain approximate 
limits, whether or not such point is connected by railroad, 
telegraph or any other of the ordinary means of communi¬ 
cation, and (2) that the transmission of the news is 
instantaneous. These two factors in radio communication 
make it possible for any one, whether he is located in a 


RADIO FOR EVERYBODY 


75 


congested city or in the country a hundred miles from 
the railroad or telegraph wire, to receive the information 
with equal dispatch. Radio transmission can be effected 
either by the international telegraph code, using dots and 
dashes, or by radio-phone. The radio-phone will probably 
present the most good to the greatest number. For the 
present, and for some time to come, so it seems, the radio 
telegraph mostly is used for this work. This necessitates, 
for the time being, at least, a knowledge of the Continental 
telegraph code, which can be readily acquired if one is but 
willing to devote a few months to intense study and prac¬ 
tice. In another chapter we shall have more to say regard¬ 
ing the code and how it can be mastered. 

Getting the Crop and Market Reports 

Crop and market reports sent out broadcast by radio 
can be received by any agency having suitable equipment. 
With the development of broadcasting by radio-phone, 
there is sure to be a demand for receiving equipment 
from many sources. Not much greater technical knowl¬ 
edge will be required to receive the reports by radio than 
to use an ordinary telephone. 

In general, at present the broadcasted reports are being 
utilized by various marketing agencies in giving to farmers 
the national crop and market reports combined with local 
market information which is distributed in other ways, 
by county farm organizations or other local agricultural 
agencies acting as centers of information for the county 
or locality, and by banks, shipping associations, commer¬ 
cial exchanges, commercial clubs and newspapers, all of 
which may serve as agencies for secondary distribution of 
the reports. In addition, the reports may be received 
direct by farmers, country elevators, dealers, shippers, and 
many others who will use the information in the transac¬ 
tion of their business. The extent to which this latter class 
will receive market reports direct remains to be seen. It 
is certain, however, that the State and county radio receiv¬ 
ing stations will be developed rapidly because of the 
economical reception and distribution of crop and market 


76 


RADIO FOR EVERYBODY 


reports through them. Certain individuals or a small 
group of individuals may find it advantageous to solicit 
the aid of radio amateurs in the community. This should 
be arranged for very carefully to ensure that the amateur 
is capable of receiving a true copy of the reports as broad¬ 
casted. 

The Radio Market News Service in the Making 

Since the radio market news service was begun experi¬ 
mentally by the United States Bureau of Markets, on 
December 15, 1920, it has developed very rapidly, so that 
at the present time the national market news is not only 
being distributed by the United States Bureau of Markets 
and Crop Estimates, but other agencies are extending the 
distribution of the national crop andimarket reports as well 
as local market reports. The service was started by the 
United States Bureau of Markets at Washington, on the 
date already mentioned. One report was sent out at 5 :00 
p. m. each day from that station. This was continued 
for four months to determine the practicability of the 
method. When it became apparent that this method would 
not only be practical but also more economical and efficient 
for certain kinds of distribution than any other agency, 
the Bureau of Markets took up the matter with the Post 
Office Department and accepted their offer to utilize the 
radio stations of the Air Mail Service in the dissemination 
of crop and market reports. At the present time, the 
larger part of the radio market news service of the Bureau 
is handled through the Post Office radio stations. Many 
of the agricultural colleges giving instruction in radio 
communication in connection with their departments of 
physics or electrical engineering, either alone or in co¬ 
operation with the State marketing agencies, have set up 
programs of broadcasting. These began with the dis¬ 
semination of weather reports from the Kansas State 
Agricultural College in 1916. Crop and market reports 
are now being broadcasted from several other colleges. 
Some privately owned stations are also broadcasting the 
information by radio-phone or by radio telegraph. 


RADIO FOR EVERYBODY 


77 


The map on page 79 shows the location of the stations 
now broadcasting. The leased wire connections of the 
Federal Bureau are also shown. The leased wire service 
of the Bureau of Markets and Crop Estimates was estab¬ 
lished in 1916 and during the past six years as many as 
17,600 miles of leased wire and 61 branch offices have 
been in operation. The leased wire has been used to carry 
reports from the markets, shipment information and re¬ 
ports from shipping points as to supply and demand, and 
f. o. b. prices. Even in its most extended form, the leased 
wire with the largest number of branch offices was never 
able to reach more than a small percentage of the people 
interested. 

The function of the leased wire will not be changed or 
curtailed by the establishment of the radio method, but 
will still be the nucleus of an effective system employing 
wired telegraph and telephone as well as radio telegraph 
and telephone. 

The Air Mail Radio Service of the Post Office Depart¬ 
ment was established primarily to give communication 
between the flying fields, in connection with the transpor¬ 
tation of mail by airplanes. These stations have to be 
available for service a large part of the day but have con¬ 
siderable time which is not necessarily occupied in the 
business of the mail service. The market reports are sent 
out on schedules which are adapted to the unoccupied 
time at the stations. This incurs merely a nominal ex¬ 
pense to the Post Office Department and inasmuch as 
the market information is obtained for other uses by the 
United States Bureau of Markets and Crop Estimates, 
the service as constituted at present incurs practically no 
additional expense to this Bureau. Because of the neces¬ 
sity of using stations not intended primarily for broadcast 
transmission but rather for interstation traffic it is not 
possible to organize as effective and complete a service 
as could be furnished by a chain of stations equipped 
solely for radio broadcast transmission. It is thought 
desirable, however, to take advantage of every facility 
at hand in order to obtain experience in handling market 


78 


RADIO FOR EVERYBODY 


news by this method and be ready to install a more effec¬ 
tive service should special facilities be made available at 
a later date. 

The Form of Crop and Market Reports 

Certain types of market information can be put into a 
form for rapid transmission by use of standard forms 
and code letters. This does not involve the ordinary use 
of code words and the necessity of coding and decoding 
the messages received, but it does make necessary the send¬ 
ing and receiving of the reports on special forms. Inas¬ 
much as the sender and the receiver use identical forms, it 
is possible by the use of code letters preceding each blank 
space in which information is to be copied, to transmit 
rapidly a large amount of information prepared in stan¬ 
dardized form. By the use of such special forms arid 
regular transmitting schedules a very effective service can 
be developed. This field has only been touched upon and 
great improvements undoubtedly will be developed in the 
handling of information in this way. 

The receiving of reports by telegraph codes, using dots 
and dashes, makes it necessary that receiving operators 
understand the international (Continental) code and be 
able to copy at least 15 words a minute. Wherever radio 
telephone communication is established, it is necessary 
only that the operator be able to adjust the radio receiving 
„ equipment properly, since the telephone reports are repro¬ 
duced in the radio receiving equipment just as they would 
be in a wall or desk telephone. Wherever it is desired 
to utilize the reports sent out by radio telephone, for pub¬ 
lication or further distribution, they can be received and 
copied by a stenographer. At the present time only a few 
special forms of reports have been developed for use in 
radio broadcast communication. Others will be developed 
from time to time as the service grows and modifications 
of the present forms undoubtedly will be made. 

In the forms already in use. two-letter code symbols ' 
are used to designate the information sent. These are used 
in two different ways: (1) A two-letter symbol is placed 



RADIO BROADCASTING STATIONS 
TRANSMITTING CROP AND MARKET REPORTS 
JAN.I) 1922 







































80 


RADIO FOR EVERYBODY 


at the beginning of the blank space which is to contain 
a certain type of information. The operator simply sends 
the two code letters and the information occupying the 
blank space. For example, in sending “New Jersey sacked 
Irish Cobbler potatoes per 100 lbs. in consuming markets, 
New York (SR) $1.75-2.10,” the operator would send 
only “(SR) $1.75-2.10.” Code letters are also used to 
designate certain options or alternatives to indicate types 
of information. For example "Demand for Wheat, Mill¬ 
ing, Strong (DK) -, Fair (DL) -, Poor (DM) 

-.” The operator would send (DK), (DL), or (DM), 

as indicating one of the three alternatives and the receiving 
operator would put a check mark in the blank space fol¬ 
lowing the letters received. Fractions are avoided wher¬ 
ever possible, but when necessary are sent as follows: 
$1.50 is sent as 1R50. 

$1.50% is sent as 1R50 and 1 DN 2. 

% of 1 cent is sent as 7 DN 8 cents. 

65% cents is sent as 65 and 7 DN 8 cents. 

All this, it will be noted, is to avoid confusion and 
error, for if there should be any doubt about the figures, 
it goes without saying that the entire value of the reports 
would be rendered worthless. 

A Question of Co-operation 

A number of States, through State bureaus of markets 
and State extension departments, are co-operating with 
the Federal Bureau of Markets and Crop Estimates in 
organizing their States to receive and utilize radio crop 
and market reports. In some cases they have established 
regular information centers which serve as distribution 
points for sending out the information through other 
channels. In other cases progressive agricultural counties 
have installed receiving equipment in connection with 
farmers’ organizations so that the information will be 
available to the county agent for further extension either 
through the daily newspapers, telephone exchanges, or 
other agencies. For the present it is probable that the 
larger application of the radio service will be through 





RADIO FOR EVERYBODY 


81 


organizations or institutions which will obtain operators 
and equipment to receive the reports and distribute them 
or make them available to individuals or groups or organi¬ 
zations of producers. As the radio-phone comes into 
more general use, many of those engaged in producing or 
marketing farm products will undoubtedly obtain equip¬ 
ment to receive the reports directly as no special trained 
operator will then be necessary. In several States radio¬ 
phone equipment is being utilized so that the reports 
which are receivea in code over the leased wire or by 
wireless may be re-transmitted by radio-phone for the 
benefit of producers in the State. 

There are many technical problems in connection with 
radio telegraphy and radio telephony that have to be con¬ 
sidered in the dissemination of broadcast reports. The 
questions of wave length and kind of transmission are both 
very important. Although the amateurs are restricted to 
the use of 200 meters or less for transmission, a large 
percentage of them are equipped to receive messages over 
a much wider range of wave lengths. Questionnaires 
sent to a limited number of amateurs having radio trans¬ 
mitting sets show that about 50 per cent are now equipped 
to receive messages transmitted on wave lengths between 
150 and 3000 meters. At first thought it would seem 
best to have the market reports transmitted on a short 
wave, but the lower wave lengths lack carrying power. 
The shorter waves have additional objections owing to 
interference. Since amateurs are licensed to transmit on 
the shorter waves, it would be very difficult for the one 
receiving market news to get solid copy—a complete and 
accurate copy of the message as sent—if several nearby 
amateurs were transmitting at the time the Post Office 
station was transmitting. Because of the greater trans¬ 
mitting range and the decreased interference, wave lengths 
of 2500, 3000 and 4000 meters are being used at the 
present time. 

The stations from which the market reports are now 
being sent by radio, the type of transmitting sets, the wave 
lengths used, and the time at which the several reports are 
sent are given in the transmitting schedule that follows: 


BROADCASTING SCHEDULE 
Post Office Department Air Mail Radio Service 

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Notice of any changes in this schedule will be broadcasted in connection with the radio reports for 
one or more days prior to the date such changes become effective. 

Copies of the forms indicated may be obtained by addressing the U. S. Bureau of Markets and Crop 
Estimates, Department of Agriculture, Washington, D. C. 


































84 


RADIO FOR EVERYBODY 


The arc stations, it is interesting to note, usually have 
a greater transmission range tlian the spark stations. 
Furthermore, it should be borne in mind that spark stations 
transmit damped waves and the arc stations transmit un¬ 
damped or continuous waves. This information is neces¬ 
sary for the selection of the proper receiving sets, and 
more will be said about this matter in the chapter on re¬ 
ceiving apparatus. 

Why Radio Telegraphy is Used at Present 

The subject of radio telegraph and radio telephone 
fransmission has been touched upon before. All things 
being equal and in readiness, radio telephone transmission 
would be the logical method to use. At present, however, 
it might be quite difficult to purchase reliable, high-power 
radio telephone equipment on the commercial market, so 
claim the authorities; furthermore, if the Bureau of Mar¬ 
kets and Crop Estimates had waited until the high-power 
telephone transmitter had become commercially available 
it would not have made the year or more of gratifying 
history which the service now has. After the broadcasting 
of market news by radio telegraph was shown to be prac¬ 
tical it was decided to use the radio transmitting stations 
of the Adr Mail Service which were already installed and 
in operation. This forms the first chain of information- 
disseminating radio stations without the delay and cost of 
constructing new ones. It is probable that these and other 
like ones will remain the master stations for some time. 

Furthermore, when the Bureau of Markets and Crop 
Estimates is successful in its work of getting the various 
States, country and private organizations to equip them¬ 
selves to receive the radio telegraph market reports, great 
advancement will have been made, for those stations will 
be ready to rebroadcast the reports by radio telephone 
when that system can be installed. In other words, a radio 
receiving station that will pick up the telegraph messages 
from the ether.will, without any alteration, pick up the 
radio telephone messages as weli. 


RADIO FOR EVERYBODY 


85 


The Bureau of Markets and Crop Estimates is under¬ 
taking to establish on an efficient basis the radio market 
news service. There undoubtedly are many obstacles in 
the way of making it an immediate, complete success, but 
so far as these have been considered up to the present time, 
they are not insurmountable and it is thought that with 
the radio operators located over the country who are trying 
to receive the reports, it may well be that the Bureau will 
be able «in a very short time to put the service on an entirely 
practical, substantial basis. 

At the present time the Bureau is entirely dependent 
upon the co-operation of the Post Office Department in 
the dissemination of the reports and they are giving their 
heartiest assistance to the Bureau in this work. It will be 
some time before receiving stations, will be distributed all 
over the country, receiving the reports regularly. A great 
many of the licensed amateur operators are receiving the 
reports and many of them are fully competent to do this. 
However, it cannot be considered as on a permanent basis 
until the State and county agencies have made provision 
for equipment and regular operators to receive the reports 
regularly. These are all controllable factors. The ap¬ 
parently uncontrollable factor which must be given con¬ 
sideration is the one of natural conditions, such as weather, 
strays and dust storms. These will be real obstacles, which 
in some localities and in some seasons will be found worse 
than in others. During midsummer, radio reception during 
daylight hours may be frequently interrupted. In fact, it 
may be impossible to receive the reports at timeTi 

It will not be necessary for our immediate needs to 
discuss the probable reasons for these peculiar atmospheric 
conditions which interfere with radio reception. It is a 
fact, however, that frequently during ithe summer months, 
the strays may completely drown out the radio signals 
picked up by the receiving set. The idea that higher 
amplification will relieve the situation is erroneous. The 
amplifier usually amplifies the strays along with the in¬ 
coming signal, so the amplified signal is often less intel¬ 
ligible than the signal received on a simple detector. The 


86 


RADIO FOR EVERYBODY 


use of high-power transmitting stations is an advantage 
in this respect. 

During storms it sometimes is not only impossible to 
receive any messages, but it may be unwise, especially if 
the storm is accompanied by lightning discharges. At such 
times the antenna should be grounded to protect the ap¬ 
paratus and no attempt made to receive radio messages. 
Although dust storms are not generally prevalent, they are 
to be reckoned with. Occasionally -the transmitting range 
of a station will be limited in a certain direction owing 
to an intercepting dust storm. There are yet other diffi¬ 
culties, such as fading of signals, which must be encoun¬ 
tered, but some of these are avoided by using the long 


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Diagrammatic explanation of the official Navy time signals as sent 
out by the Arlington station. These signals are re-transmitted by 
several of the broadcasting stations. Each black dot represents a 
transmitted dot, while the white dots represent spaces. The time 
signals start five minutes before 12 o’clock noon and 10 o’clock P. M. 
and follow the schedule here depicted, terminating with a dash 
on the hour, followed by a four dot space and the call letters 

“N A A.” 


waves. However, after taking all of these things into 
consideration it is quite probable that a high percentage 
of completeness may be anticipated in handling this kind 
of service. 

From General News to Time Signals 

Then there are other radio telegraph broadcasting serv¬ 
ices available to the owner of a receiving set. The most 
important of these is the broadcasting of time signals 







RADIO FOR EVERYBODY 


87 


weather bulletins by the high power naval station at 
Arlington, V a. The time signals and weather bulletins are 
sent out twice daily on a wave length of 2500 meters, at 
11.55 a. m. and 9.55 p. m. The signals begin at these 
times and the final dash is sent at 12 noon and 10 p. m. 
and are astronomically correct for the meridian of 75 
degrees west of Greenwich. 

The signals are sent out as follows: Beginning at 11.55 
a. m. or 9.55 p. m. a dot is sent every second for the first 
thirty seconds, then one second is skipped, and beginning 
with the thirty-first second to the fifty-fifth second the 
dots are again sent, one each second. The last five seconds 
of the first minute are skipped, and the signals begin 
again at exactly the beginning of the fifty-sixth minute. 
The same schedule is maintained through the fifty-seventh 
and fifty-eighth minutes right through until the fiftieth 
second of the last minute is attained. Then comes a 
silence or blank for ten seconds, and the next dash is 
exactly 12 o’clock noon or 10 o’clock in the evening, as 
the case may be. The general scheme of the time signals 
is perhaps made clearer by studying the accompanying 
chart. This time is absolutely accurate and is employed 
by ships at sea for the setting of chronometers, and by 
progressive jewelers and others desiring an accurate time 
service. The signals are transmitted at Arlington, to be 
sure, but the dots originate in a master clock at the Naval 
Observatory. 

No sooner are the time signals over than the Arlington 
station sends out the weather bulletin in code—a code, 
however, which is quite simple to understand. A weather 
bulletin, as sent out by Arlington, runs as follows: 

QST de NAA, USWB, S01081—T02261— 
DB0251 — H00844 — C01261 — K00441— 

P1242. 

All of which means, when reduced to plain English, 
that the letters stand for K—Key West, Fla.; S—Sidney, 
Nova Scotia; T—'Nantucket, R. I.; DB—Delaware Break¬ 
water; H—Cape Hatteras, N. C.; C—Charleston, S. C.; 
p—Pensacola, Fla.; B—Bermuda. The first -three figures 


88 


RADIO FOR EVERYBODY 


following the letter are 
various places. Taking 
S01081, the figures 010 
of 30.10 inches, and the 


N 



How numerals are used to 
indicate the points of the 
compass in connection with 
the direction of wind num¬ 
erals used in the Arlington 
weather bulletins. 


the barometer reading at the 
the first set of figures sent out, 
represent the barometer reading 
next figure represents the direc¬ 
tion of the wind, which hap¬ 
pens to be NW in this case, 
since the numerals begin with 
1 for North, 2 for NE, 3 
for E, 4 for SE, and so on, 
as shown in the accompanying 
diagram, reading around the 
compass in the same direction 
as travel the hands of a clock. 
The last numeral means the 
velocity of the wind, and the 
following table gives the fig¬ 
ures and their values in statute 
miles (1.15 nautical miles) per 
hour: 


0—Calm. 

1— Light air. 

2— Light breezes .. 

3— Gentle breezes . 

4— Moderate breeze 

5— Fresh breezes... 

6— Strong breezes.. 

7— Moderate gale.. 

8— Fresh gale .... 

9— Strong gale . .. 

10— Whole gale .... 

11— Storm . 

12— Hurricane . 


0 to 3 miles per hour 
8 miles per hour 
13 miles per hour 
18 miles per hour 
23 miles per hour 
28 miles per hour 
34 miles per hour 
40 miles per hour 
48 miles per hour 
56 miles per hour 
65 miles per 4iour 
75 miles per hour 
90 miles per hour 


Now, therefore, take the code signal K00441. The K, 
it will be noted, stands for Key West; the figure 004 
states that the barometer stands at 30.04 inches; the next 
figure indicates that the direction of the wind is South 
East, and the last figure, 1, represents the velocity of the 













89 


RADIO FOR EVERYBODY 

fr 

wind, which in this instance is light air, or a breeze having 
a velocity of only eight miles an hour. 

1 he Arlington time signals and weather bulletins are 
sent on a wave length of 2500 meters. The call letters of 
this station are N A A, which are signed immediately 
after the final dash in the time signals. Fortunately, the 
weather bulletins are sent at a slow, even speed, so that a 
person with only a slight training in the telegraph code 
can copy down the letters and figures. It is well to men¬ 
tion here that the bulletins are sent out by automatic 
transmitter, so that the dots and dashes are perfectly 
formed. 

Certain radio-phone broadcasting stations give out the 
time signals by radio-phone. This is accomplished by 
receiving the time signals from Arlington on a long-range 
receiving set, and then amplifying these signals until they 
are sufficiently loud in a telephone receiver which is held 
up to the transmitter microphone for retransmission via 
the radio-phone. In this manner the persons in the vicinity 
of the radio-phone broadcasting station can receive the 
time signals without having to tune up to the long wave 
length of the Arlington station. Furthermore, the radio¬ 
phone broadcasting stations receive the weather bulletins 
and broadcast them 'in plain English, which requires, of 
course, absolutely no knowledge of the telegraph code. 

Time signals and Weather bulletins are broadcasted by 
other naval stations. Thus the Great Lakes station NAJ. 
transmitting on 1512 meters, sends out time signals at 10 
p. m. (90th meridian time). Also, North Head, Wash., 
San Francisco, Cal., and San Diego, Cal., transmit the 
time signals at 10 p. m. (120th meridian time), followed 
by the weather bulletins. The Pacific coast stations broad¬ 
cast the information first on their usual working wave 
length, next on 952 meters, and finally on 600 meters. 
Reports from these stations are preceded by “USWBSF,” 
the first four letters standing for “United States Weather 
Bureau” and the last two for San Francisco. 

Weather reports from the Pacific coast stations are 
broadcasted at 8 a. m., noon. 4 p. m., and 8.00 p. m. Cape 


90 


RADIO FOR EVERYBODY 


Blanco broadcasts Tatoosh, N'orth Head and Eureka 
weather after local report. At 8 a. m. and 8 p. m. Eureka 
broadcasts the 6 a. m. and 6 p. m. weather conditions at 
Farallones; Farallones, in turn, broadcasts the 6 a. m. 
and 6 p. m. weather conditions at Eureka, and 7 a. m. 
and 7 p. m. weather conditions at the Farallones. 

Aside from the Atlantic coast abbreviations already 


given, the following are also necessary: 

Great Lake Region 

Duluth . DU 

Marquette . M 

Sault Ste. Marie. U 

Green Bay. G 

Chicago . CH 

Alpena... L 

Detroit. D 

Cleveland. V 

Buffalo. F 

Pacific Coast Region 

Tatoosh. T 

North Head . NH 

Eureka . i. E 

San Francisco. SF 

San Diego. SD 


Aside from the time signals and weather bulletins, there 
are various press broadcasting services operating from 
time to time. Some of these have the amateur very much 
in mind, and in consequence transmit the press items at a 
slow rate of speed. All in all, there is quite as much 
interesting news and general information to be obtained 
through the radio telegraph broadcasting as there is by 
radio-phone, although it goes without saying that the first 
can be received by any one without training of any kind, 
while the second presupposes at least a working knowledge 
of the dot-and-dash language of the telegraph. 

From Radio Telegraph to Radio-Phone 

As this is being written word comes to us to the effect 
that Government information is shortly to be broadcasted 

















RADIO FOR EVERYBODY 


91 


by radio-phone, this service taking the place of the present 
radio market news service of the United States Bureau of 
Markets and Crop Estimates, as described early in this 
chapter. A radio-phone has recently been installed on the 
top floor of the United States Post Office Building in 
W ashington, D. C\, and sufficient power is now available 
to broadcast Governmental messages to the public over a 
wide area. Governmental information—data assembled 
by the various departmental bureaus relating to farming, 
fruit-growing, lumbering, mining, and general knowledge 
—is being distributed throughout the United States. Con¬ 
gress is being urged to establish a “Bureau of Communi¬ 
cation” in the Post Office Department, appropriating $500,- 
000 annually for its maintenance, thus designating a clear¬ 
ing house for the broadcasting of knowledge of a varying 
nature by radio, catering to the diverse interests of 
110,000,000 citizens. 

The abandonment of radio telegraphy in favor of radio¬ 
telephony as a vehicle for the transmission of weather and 
market information, which service was introduced April 
15, 1921, marks the advent of a hitherto unprecedented 
popularity for the distribution of Governmental data by 
radio communication. Radio telegraphy, after eight and 
one-half months of practical application, proved to be too 
specialized in nature, involving, as it does, a knowledge 
of the international telegraph code for use as a medium 
of circulating weather forecasts and the fluctuating ten¬ 
dencies of the markets. Hence the decision to adopt radio 
telephony as the distributing vehicle, the operation of the 
radio-phone being little more complicated than the use 
of a common telephone, a sewing machine, or phonograph. 
It is contemplated that instant and almost universal popu¬ 
larity will be accorded the latter system. 

The present installation in the Post Office Department 
Building at Washington is the first unit of its kind to 
be placed in operation, and claims to novelty may be ad¬ 
vanced with regard to its mechanism. This wireless 
telephone puts 14 amperes into the antenna at. 1160 meters 
wave length, which is a goodly amount of radio energy, as 
radio transmitters go. The modulation of the voice is 


92 


RADIO FOR EVERYBODY 


said to approach perfection. Preliminary tests have suc¬ 
ceeded in flinging the voice, so to speak, as far west as 
Bryan, Ohio, and southward to Atlanta, Georgia, dis¬ 
tances exceeding 1,000 miles. The transmitter is quite 
flexible, so that the service may be varied to suit varying 
operating conditions if necessary. 

Contingent upon the will of Congress in appropriating 
the requested $500,000 for establishment of a “Bureau of 
Communication,” the service will be extended in its reach 
as well as expanded in nature. Isolated areas, as well as 
frequented points in the United States, will be visited by 
this hurry-up method of spreading the news. At present 
there are eight radio stations, as already described, orig¬ 
inally established in conjunction with the transportation of 
mail by airplane, used as distributing agencies of market 
and weather reports. These are located at Washington, 
D. C.; Cincinnati, Ohio; Omaha and North Platte, Neb.; 
Rock Springs, Wyo.; Elko and Reno, Nev. Radio-phone 
stations in prospect, by reason of the expansion of the 
service, will be located in Georgia, Texas, California, Mon¬ 
tana, Illinois and at some point in the New England 
States. A survey being conducted by the Post Office 
Department will determine the exact locations of these 
information-distributing stations. 

The Post Office Department voices, the belief that the 
widespread dissemination of Governmental knowledge will 
not only prove of economical value to a varied citizenry 
of the United States, but will serve as a leavening process 
in Americanizing the increasing element of foreign popu¬ 
lation in our midst. The Post Office Department will not 
only give circulation to market news and weather fore¬ 
casts, in the event that Congress sanctions an enlargement 
of the service, but the different Government bureaus will 
be drawn upon for facts pertaining to discoveries and 
developments that will serve the diverse interests of the 
farmer, miner, rancher, fruit-grower, forester and lumber¬ 
man. Then, too, the public in general can appropriate to 
advantage much of the information circulating through 
space by reason of its practical value and entertaining 
quality. 


Chapter IV. 


RECEIVING EQUIPMENT AND THE 
INTERCEPTION OF RADIO WAVES 

T HERE is nothing complicated about radio reception. 

The apparatus may he of the simplest sort, if the 
distance to be spanned is relatively small; virtually no 
experience is required, for anyone can turn the few 
knobs and adjust the detector; no licenses are required, 
and anyone can intercept radio waves without formality 
of any kind; and the cost is low, considering the wonder¬ 
ful possibilities of a radio receiving set. It is only when 
one desires to span great distances and to have the dots 
and dashes or the radio-phone music amplified so as to 
he heard throughout a room, without the use of the usual 
telephone head set, that the cost mounts up. Even so, the 
cost is still no greater than that of a good phonograph, and 
certainly less than half the cost of a low-priced automo¬ 
bile. After all, it is a question of what is expected of 
the receiving equipment, and successful results demand 
that the receiving equipment be fitted to the requirements. 

Essentials of Radio Reception 

No matter how simple a receiving set may be and how 
modest the requirements, there are certain essentials which 
must be provided. Thus we have: 

First —One or more wires elevated from the ground 
and properly insulated, to form the antenna or the aerial. 
The purpose of the antenna, or aerial, is to intercept the 
radio waves and to convey them to the receiving apparatus. 


94 


RADIO FOR EVERYBODY 


An alternative to the aerial is the loop, which is simply 
a large frame with several turns of wire, which may be 
used indoors with fair results. 

Second —A good connection with the ground, which 
may take the form of a connection with a gas, water, or 
steam pipe. In the absence of any one of these pipes, such 
as in remote country districts, a good ground may be ob¬ 
tained in other ways, as described further on. Again, 
the ground may take the form of an insulated network 
of wires, placed below the aerial but elevated from the 
ground by a few feet. Such a ground is known as a 
counterpoise, and is frequently used. No ground is re¬ 
quired when a loop is employed instead of an aerial. 

Third —A means of altering the wave length of the 
aerial circuit and the receiving apparatus, so as to inter¬ 
cept and detect any desired radio waves to the more or 
less complete exclusion of undesired waves. Tuning is 
accomplished by a wide variety of instruments and meth¬ 
ods, as will be explained. 

Fourth —A means of changing the frequency of the 
incoming waves from radio frequency to audio frequency 
so that they may be heard. The instrument that accom¬ 
plishes this result is known as the detector, and is of 
the crystal type or the vacuum tube type. 

Fifth —A companion instrument to the detector, which 
takes the audio frequency current delivered by the detec¬ 
tor, after the latter has converted the radio frequency 
into audio frequency current, and makes it audible to 
the human ear. This instrument may be any form of 
telephone receiver, ranging from the single receiver to 
the head set and to the loud-speaker. 

The first step, then, is to consider the aerial or an¬ 
tenna for receiving purposes. While the same aerial or 
antenna may be used for both receiving and transmitting 
purposes, as a general thing these purposes are by no 
means interchangeable if really efficient results are de¬ 
sired. Thus the ideal antenna for receiving—antenna, 
by the way, is a happier term for the receiving end than 
aerial, the latter applying more particularly to transmis- 


RADIO FOR EVERYBODY 


95 


sion work—is a single wire, insulated at both ends, ele¬ 
vated some 20 or more feet from the ground and mea¬ 
suring 150 feet in length. A shorter wire makes for a 
lower efficiency, while a longer wire, strange as it may 
seem, also detracts from the receiving efficiency. The 
reason for this is that the wave length of the aerial 
should be as nearly as possible that of the radio waves to 
be intercepted. Otherwise, in the case of a shorter wire, 
it is necessary to add inductance in order to bring up the 
wave length, and such inductance means some loss of 
energy. Furthermore, a shorter wire will not intercept 
as much of the radio waves as a longer one. Now, on the 
other hand, a longer wire intercepts more of the radio 



How a receiving antenna may be installed in the country. The 
single wire may be run from the house to a barn, tree, clothes 

pole or other support. 


wave, but it is necessary to use either a variable or fixed 
condenser in series with the antenna in order to bring 
down the wave length, and such practice means a loss of 
energy. O'f course, we are considering the receiving set 
on the basis of amateur and radio-phone reception. If one 
desires to receive the long-wave commercial stations, a 
longer wire is quite satisfactory. Indeed, for the best 
kind of work it may be well to have several antennae, 
arranged for various classes of service. 

The Aerial and the Ground for Receiving 

As for the kind of wire to use, there is considerable 
latitude; indeed, in this general subject of antennae for 
receiving purposes there are no fixed rules to go by. 








96 


RADIO FOR EVERYBODY 


Various kinds of wire are used, among these being plain 
aluminum wire, which has the advantage of being exceed¬ 
ingly light and quite low in cost; plain copper wire, which, 
of course, is an excellent conductor, although somewhat 
costly, especially in the larger sizes; hard-drawn copper 
wire, which has all the advantages of plain copper, plus 
greater strength; copper-clad steel wire, which has great 
strength coupled with good conductivity; stranded phos¬ 
phor-bronze wire, which has long been the standard aerial 
wire in commercial and Government work; and annunci¬ 
ator or bell wire, which is insulated. The last-mentioned 



Materials with which to erect the antenna, compris¬ 
ing a coil of bare copper or copper-clad steel wire, 
insulators, ground clamp, insulated wire for lead-in, 
porcelain tube to insulate lead-in passing into build¬ 
ing, and a lightning arrester. 


wire may sound freakish and merely an improvision; but 
as a matter of fact the insulation makes little difference. 
Why? Simply because if the insulation were not there, 
the space immediately surrounding the copper wire would 
be taken up by air, and the air is about as much of an 
insulator as the usual cotton and paraffin insulation. 
Hence it makes little difference one way or the other, and 
annunciator or bell wire recommends itself in many in¬ 
stances because it is so easy to obtain. A pound of No. 
18 wire is sufficient for a good single-wire antenna. 

Aluminum wire is not recommended very enthusiastic¬ 
ally by the author. Back in the early days of amateur 




RADIO FOR EVERYBODY 


97 


radio, when we used to spend our hard-earned money by 
the cent rather than by the dollar, aluminum wire was 
widely employed because a good many feet of it came 
with each pound. However, it has not the conductivity 
of copper by a good margin, and even when using No. 
14 size it is not as good as No. 18 copper. Furthermore, 
it is difficult to solder aluminum wire joints, yet they 
should be soldered. If the joints are not soldered, water 
gets into them and oxidizes the aluminum wire. The 
oxide takes the form of a white crust, and is of such 
high resistance that it reduces the efficiency of the antenna 
materially. Hence aluminum wire should not be used ex¬ 
cept where cost is a prime essential, and even so, a small 
sized copper wire is preferable. 

Copper-clad steel wire is almost as good as solid copper, 
and costs considerably less. It is the kind of wire that 
is supplied with the usual antenna equipment as sold by 
wireless dealers. Hard-drawn copper wire of No. 12 or 
No. 14 guage is satisfactory for antenna construction; 
however, stranded silcon bronze or phosphor bronze wire 
is more durable and will stand greater strains. 

Now then, having selected the wire, the next step is 
to erect the antenna. Supports are sought, since for re¬ 
ceiving purposes the height of the antenna is not so im¬ 
portant and the antenna may be supported by any suitable 
object, such as a house, tree, flag-pole, clothes-pole, and 
so on, making masts or supporting towers unnecessary. 
If possible, the wire should be horizontal, which means 
that the supports at both ends must be of the same height. 

It is necessary to insulate the antenna wire. This is 
done by placing little porcelain knobs or porcelain cleats, 
such as are used in exposed electric light wiring, at each 
end of the wire, as shown in the accompanying sketch. 
Such improvised insulators will serve quite nicely for 
ordinary installations, but if the antenna is apt to be sub¬ 
jected to considerable strains from high winds as well 
as coatings of ice, it may be well to substitute regular 
antenna insulators. These take the form of special 
moulded electrose insulators, with heavy galvanized rings 


98 


RADIO FOR EVERYBODY 



Simple way to insulate and fasten the farther end or free 
end of a single wire antenna. 


moulded right into the brown insulating material. The 
insulator proper is provided with many deep grooves, so 
as to lengthen the surface of the insulator and therefore 
increase its resistance to leakage or loss. Small electrose 
insulators will do for the receiving station, if placed at 
the ends of each antenna wire, between the wire and the 
support. 

Another popular form of antenna insulator is one made 



How the nearer end or lead-in end of the antenna is fastened 
and insulated. The lead-in wire is fastened to the antenna 
wire by means of a connector, or is soldered so as to insure 
a perfect and lasting joint. 




RADIO FOR EVERYBODY 


99 


of micarta, with a metal lined hole at each end. This 
kind of insulator is supplied with an antenna equipment 
now on the market, and has the advantages of considerable 
mechanical strength with good insulating properties. 

In the country the erection of the antenna is a simple 
matter, for there are virtually no restrictions such as one 
encounters in the crowded city. Thus the antenna wire 
may be run from the roof of the house to the roof of 
the barn, or even from the second floor of the house to 
the roof of the barn. If no barn is available, then the 
farther end of the wire may be supported by a clothes- 
pole or tall tree. 

In connection with the portable radio set which is very 
much in vogue during the summer vacation, the antenna 
presents an interesting problem. Obviously, it is possible 
to erect an antenna along the usual lines, but if the por¬ 
table set lives up to its name and is shifted about from day 
to day, it becomes necessary to employ the simplest possible 
antenna and to use materials which lend themselves to 
much handling without breakage or entanglement. In this 
connection there is an excellent braided copper cable which 
is made in the form of a woven tube. This braided copper 
cable is extremely light, readily handled, and lends itself 
to unwinding and rewinding many times because of its 
great flexibility. 

The braided copper cable is considerable larger in dia¬ 
meter than the usual copper wire employed for antennae. 
Thus it presents greater surface to the radio currents, and 
since these currents, by virtue of their extreme frequency, 
travel on the surface of a conductor, the greater the surface 
the better the cable for antenna purposes. The author has 
found the woven copper cable to be most efficient. 

In the city, the antenna presents a problem. What with 
congested conditions and a none tao obliging landlord, • 
the radio enthusiast is often forced to resort to a little 
strategy. The author, only recently a resident of the 
suburbs, traveled a rather thorny path in pursuit of radio 
while residing in New York City. One antenna after 






v ) 


100 


RADIO FOR EVERYBODY 


another was removed by a highly militant janitor, carrying 
out the instructions of an overbearing landlord. The 
-antennae took all kinds of forms, ranging from single wires 



simple, single-wire l-tvpe 


How the I.-type single wire antenna is installed. Such an¬ 
tennae should not be shorter than 60 feet and not longer than 
150 feet for best results in the reception of short waves such 
as are used in amateur and radio-phone work. 


running from one house to another across a court or large 
open space, to a number of wires supported on poles or 
supported by the dumbwaiter houses on the roof. Finally, 
the author simply ran a single wire down a chimney, from 
the roof to the cellar, a distance of about 75 feet. This 
wire was never detected, and it was tapped in the kitchen 
of the apartment, through a flue that led into the chimney. 
A poor antenna at best, it served to receive the Newark 
radio-phone service some 15 miles distant. 

All sorts of improvisions may be resorted to when an 
outdoor antenna is not practical. A metal bedstead, the 



^INSULATOR 

INSULATOR-^ 




^-LEAD-IN 


-i 

&- -- - - ^- 




T'TYPE ANTENNA, TAPPED IN CENTER 

Arrangement of a T-type single wire antenna. When the 
antenna runs longer than 150 feet, it may he desirable to tap 
it in the center for the lead-in, provided the lead-in can he 
dropped straight down to the receiving apparatus. 


telephone line with a fixed condenser in series, the bell 
wiring of the house, the fire-escapes, an indoor antenna 
of any shape and size—all these improvisions are possible 
for nearby signals. 































RADIO FOR EVERYBODY 


101 


So far, only single wire antenna have been dealt with. 
The wire is tapped at one end by another length of wire 
leading to the receiving instruments. This second wire is 
called the lead-in, and it is preferable to have it of insulated 
wire, so that if it touches a wall or roof coping or other 
object there will not be the leakage that would occur with 
bare wire. 

But supposing the antenna is stretched over a greater 
distance than say 125 or 150 feet, and the receiving station 
must be located near the middle of the span, then what? 
Simple enough. The antennae so far described are called 
the L-type, because the antenna proper and the lead-in 
form an inverted L shape. If the antenna is to be 200 or 



v-type antenna 

The V-type antenna, consisting of two wires of about equal 
length, diverging to two different supports. 


300 feet long, then the tap is taken at the center, and to all 
intents and purposes the antenna is equivalent to two 
single wires 100 or 150 feet long. In other words, the 
wave-length of the long wire is halved by tapping it at 
the center. This type of antenna is known as the T-type. 
Another modification of this type is the V-type, in which 
two wires of about the same length run from the lead-in, 
at one end, divergingly to two more or less separated sup¬ 
ports at the farther end. This form of antenna has the 
same wave-length as the average of the two wires, and is 
more efficient than a single wire. 

Then there is the umbrella type which must be employed 
where a stretch of over 40 feet is not to be had. In this 
case a tall pole must be used as the center support, and 
the wires numbering six to ten, radiate downward in all 


























102 


RADIO FOR EVERYBODY 


directions, being insulated at the top and bottom ends. 
The lower end of each wire should be 20 feet from the 
base of the pole, so as to obtain as much spread as possible. 
The lead-in wire is taken from the top, the various wires 
being connected together and spliced to the lead-in wire. 
The erection of the umbrella type is somewhat complicated, 
as compared with the simple single wire antennae, and is 
therefore not recommended for receiving purposes except 
in cases of absolute necessity. 

For receiving purposes, a multi-wire L-type or T-type 
antenna is not necessary, hence a description of the multi¬ 
wire antenna e—or more 
properly called aerials, since 
they are to be used for trans¬ 
mitting—will be left for the 
chapter dealing with trans¬ 
mission. 

The lead-in connects the 
antenna with the receiving 
instruments. One of the 
problems is to bring the an¬ 
tenna through the wall or 
window into the station, no 
matter where it may be lo¬ 
cated. Some amateurs pre¬ 
fer to bore a hole through the glass pane of a window, but 
this is a somewhat tedious job and one that is apt to end 
in a disaster unless there is considerable skill behind it. A 
better plan is to cut a board in order that it will fit in the 
window frame below the partly raised window, so as to 
keep out the air. The window is brought down on the 
board. A hole is made in the board and provided with a 
porcelain tube insulator, through which is passed the lead- 
in. The lightning switch or arrester can be mounted on 
the board, if desired. 

Then there is the ground connection, which is highly 
important. Indeed, the effectiveness of the antenna system 
depends largely upon the character of the ground connec¬ 
tion. The most practical ground connection is the water 



OM&REU.A TYPE ANTENNA 
The umbrella type antenna, 
which is only employed w r hen 
it is impossible to obtain a 
sufficient span for the antenna. 
This type is quite popular in 
transmission work. 





RADIO FOR EVERYBODY 


103 


supply system. Where this is not available, pipes com 
nected with the heating or gas system may be used, al¬ 
though these are to be regarded with some suspicion. 
Sometimes a non-conducting length of pipe is inserted in 
the gas line before it reaches the earth, so that it is not a 
true “ground” connection. However, the results obtained 
soon disclose whether the pipe is grounded or not. 

At any rate, the pipe selected is scraped with a knife 



A convenient manner in which to bring the lead-in wire 
into the house. A board of about the same width as the 
window frame is inserted at the bottom or top of the win¬ 
dow frame, and the window is then pushed against it so as 
to shut out the air in cold weather. The lead-in passes 
through a hole in the board, which may be insulated. Thus 
the window can be raised or lowered without trouble. 


or rubbed clean with sandpaper until it is bright, and 
connection is made by means of ground damps, which 
can be obtained at any electrical supply store, or by wrap¬ 
ping ten or more turns of copper wire about the cleaned 
section of the pipe, good and tightly so as to make firm 
contact. No. 14 wire is preferable for the ground lead, 
although anything up to No. 20 will do. Naturally, the 
insulation is removed from the wire at the point where it 
makes contact with the pipe. If possible, the wire should 


































104 


RADIO FOR EVERYBODY 


be soldered, for one cannot take too much pains with the 
ground connection. More receiving troubles originate 
with a poor ground connection than from any other 
source, for the good and sufficient reason that this end 
of the installation seems so simple that it is often slighted. 
Too much is taken for granted. However, if no solder is 
used, then it is well to wind insulating or friction tape 
about the connection, so as to hold it firmly in position 
and to prevent corrosion between the copper wire and 
the pipe. 

Where the above-mentioned means of ground connec¬ 
tion are not available, wires or plates may be buried in 
the earth and connected to the apparatus. Such wires or 
plates should include an area of at least 30 square feet, 
buried in damp soil. Another method is to attach the 
ground wire to a metal bucket which is then lowered into 
a well, a brook, a pond or a lake. 

Doing Away with the Ground Connection—The 

Counterpoise 

There are places where a ground connection is out of 
the question. Take, for instance, desert country, where 
the soil is sandy and without moisture of any kind. Or 
again, take rocky country, where there is just a thin layer 
of soil over solid rock. Obviously, a ground is out of the 
question. It then becomes necessary to resort to what is 
known as the counterpoise, which consists of at least the 
same number of wires as the antenna, suspended beneath 
the antenna and used in place of the usual ground connec¬ 
tion. The counterpoise wires should be elevated but a 
few feet from the ground, and just as carefully insulated 
as the antenna wires. 

In aircraft, the counterpoise form of ground is em¬ 
ployed. It must be evident that no ground connection is 
possible when the machine is in flight. So the antenna 
consists of one or more wires which are paid out while 
the machine is in flight, and which trail behind some 100 
•or more feet in length, while the ground is represented 


RADIO FOR EVERYBODY 


105 


by a counterpoise made up of all the metal fittings and 
stay wires and control cables of the machine. 

The counterpoise is especially efficient and almost neces¬ 
sary in conjunction with continuous wave transmission, as 
will be described farther on when we come to transmitting 
equipment. 

When the summer comes along in such localities where 
thunder storms are common occurrences, it is necessary 
to give some consideration to lightning. The antenna, 



How the lightning switch is installed. It should always be 
installed on the outside of the building, with the ground wire 
going as straight as possible. The blade of the switch is con¬ 
nected with the antenna, one jaw is connected with the receiving 
set, and the other is connected directly to the ground. Thus 
the antenna may be connected with the receiving set or 

“grounded.” 

after all, presents but a small target to lightning, but even 
so it is well not to take chances. Just as electric power 
lines and telephone and telegraph lines must be protected 
against lightning, so must the antenna be provided with 
some protective device. The Fire Underwriters require 
the installation of a lightning switch or protective device, 






































































106 


RADIO FOR EVERYBODY 


and this should be done as a precautionary measure. The 
approved type of lightning switch is a single-pole, double¬ 
throw, 600-volt, 100 ampere, knife switch, mounted on a 
composition base. The slate base so often provided with 
such switches is not satisfactory, because *it absorbs 
moisture and causes quite a little leakage of the radio 
currents when used in this manner. Lightning switches 
are required to be mounted on the outside of the building, 
and the ground connection may be made to an iron pipe 
driven several feet into the ground. This connection 
should foe made with weatherproof copper wire, No. 6 
B. & S. guage or larger. It may well be worth while for 
the radio enthusiast to mount the switch on electrose pil¬ 
lars, since these offer the maximum insulation, and the 
pillars, in turn, can be mounted on a stout oak board. 

However, where only receiving apparatus is being used 
—and we are dealing with receiving apparatus only in this 
chapter—lightning protection may be obtained by the use 
of a vacuum-gap protective device. This device should 
be installed in place of the lightning switch and should be 
permanently connected to both the antenna and ground 
wires. The vacuum-gap lightning protector is made in 
several different types both for indoor and outdoor in¬ 
stallation. The outdoor type is preferable, because the 
shortest possible route to the ground should be provided 
for any possible lightning charge. All radio supply 
houses handle the various types of vacuum-gap lightning 
protector. 

% 

Using the Loop in Place of Antenna and Ground 

9 

Interesting results may be obtained by using a loop in 
place of the usual antenna and ground, although it is well 
to remember that the loop is by no means as effective as 
an outdoor antenna. A loop consists of a suitable wooden 
frame on which are wound a number of turns of bare or 
insulated wire. The frame should be suspended or mounted 
in such a manner as to permit of being swung in all direc¬ 
tions. The loop receives best when it is pointing edge on 
towards the transmitter, and it is this characteristic of the 


RADIO FOR EVERYBODY 


107 


loop which makes it interesting. It indicates the direction 
of the transmitter being intercepted, and this forms the 
basis of the radio compass which has found such wide 
use in modern navigation. 

Loops are of two general types: there is the spiral loop, 
which is of the flat type, inasmuch as all turns are in the 



A solenoidal type loop of simple construction, 
which can be used in place of the usual antenna. 


same vertical plane and each turn encloses an area smaller 
than the preceding turn ; and there is the solenoid loop, in 
which the coils are all of the same dimensions, spreading 
out horizontally so as to form a square helix. A loop 
only three feet in diameter is sufficiently large to pick up 







































108 


RADIO FOR EVERYBODY 


radio-phone broadcasting stations a few miles distant, and 
larger loops may be employed at greater distances. Trans¬ 
atlantic reception is effected by means of loops, which 
have the advantage of reducing atmospheric disturbances 
and other interference to a minimum. However, loops 



hence amplifiers must be resorted to when using loops. 
Since the number of turns comprising any loop depends 
largely on the wave length desired and the dimensions 
of the frame, it is best to decide the exact number in each 
case by experimentation. To this end the loop should 
be made with bare wire so that one can tap any number of 























KADIO FOR EVERYBOD\ 


109 


turns, or the insulated wire should be bared at certain 
points so as to permit of tapping. More will be said 
about loops in the chapter on operating the receiver. 



One of the neatest forms of loop. The turns of wire are spaced 
about one inch apart for the best results. 


The Irreducible Minimum Among Receivers 

With the antenna and ground accounted for, the next 
step is to consider receiving equipment. The simplest 
receiving equipment comprises a detector and a single 
telephone receiver. The detector, as we have already 
learned, is a device which changes the frequency of the 
incoming waves from radio frequency to audio frequency 



















110 


RADIO FOR EVERYBODY 


so that they may be heard in the telephone receiver. Let 
us consider the simplest kind of detector. 

Nothing could be less complicated or less expensive 
than the crystal detector. It makes use of one of several 
different kinds of mineral crystals which possess the de¬ 
sirable characteristics. The most popular crystal body 
today is galena (lead sulphide), a silvery gray mineral 
which breaks in squares with mirror-like surfaces. Rest¬ 
ing on the galena crystal is a fine piece of wire, and it is 


GALENA DETECTOR WITH SPRING 



A crystal detector unit. In this case two detectors are mounted 
on the same base, with a switch for selecting either detector. 

the contact between the crystal and the wire which does 
the rectifying of the high frequency radio energy, of the 
order of 20,000 to 6,000,000 changes of direction per sec¬ 
ond, to impulses of varying strength travelings in one 
direction only, and therefore capable of operating a tele¬ 
phone receiver. Sometimes another crystal is employed 
in contact with the galena, in place of the wire. 

Now with all crystal detectors the matter of adjustment 
is an important one. Unfortunately, the crystals are not 
uniformly sensitive. Here and there on a given surface 
there are sensitive spots, and these must be sought out. 
Hence when using a crystal detector the wire member 
must be shifted about on the surface of the galena crystal 
until a sensitive spot is found. Once a sensitive spot is 
found, the detector need not be readjusted for some time. 





RADIO FOR EVERYBODY 


111 


However, if it is jarred the sensitive contact may be lost, 
and readjustment is then necessary. 

While the crystal detector is far more sensitive than the 
earlier forms of detector employed during the pioneer 
days of radio communication, it is not nearly as efficient 
as the vacuum tube type, which will be described further 
on. However, the crystal type is inexpensive and may 
be used with the simplest kind of equipment. It requires 
no batteries of any kind. 

The simplest receiving set, therefore, consists of the 
antenna and ground connected to a plain crystal detector, 
with a telephone receiver in parallel; and no attempt is 
made to tune such an arrangement. At short distances 
from a powerful radio-phone or radio telegraph station, a 
crude receiving set of this kind serves quite nicely. 
Indeed, from France comes the little receiving set which 
may be carried about in one’s pocket. It comprises a 
telephone receiver, on the back of which is mounted a 
crystal detector. Such an arrangement is used in Paris 
for receiving time signals from the powerful Eiffel tower, 
and even radio-phone concerts are picked up at consider¬ 
able distances outside the French metropolis, when using 
this diminutive receiver. Instead of using a single wire 
resting on the galena crystal, this device has ten wires 
resting on ten different places on the crystal, and a switch 
is provided so that the operator can select any one of the 
ten wires. Obviously, one or more of the wires are almost 
certain to be resting on a sensitive spot; if not, the crystal 
can be shifted slightly, so as to give ten new spots. This 
idea is truly ingenious, and works out very well in prac¬ 
tice. The little set is provided with tiny spools containing 
the necessary connecting cords and clips, so that one can 
hook up to any suitable ground and to anything that will 
act as an antenna. The framework of a large awning, 
the fire escape, an iron bedstead, an umbrella—all these 
and other similar metallic objects may be used for receiv¬ 
ing messages from powerful stations but a very short 
distance away. 


112 RADIO FOR EVERYBODY 

Simplicity Combined with Efficiency 

With no provision made for tuning, a receiving set must, 
perforce be of a low order of efficiency. Lurthermore, 
all signals come in at the same time, if several transmitters 

are working in the immediate 
vicinity. By providing the 
simplest kind of tuning device, 
the efficiency of the crystal de¬ 
tector and telephone receiver is 
immediately improved. 

There are several simple types 
of tuning devices. One of these 
is the inductance coil, which con¬ 
sists of a large number of turns 
of copper wire, wound in a single 
layer on a solid mandrel or tube, 
and provided with some means 
for varying the number of turns 
of wire which are used. A 
switch may be employed, with 
The simplest receiving set contact points so arranged as to 

that will give fair results, " ° - 

using a rough tuning coil, represent say every ten turns ot 

wire, in order that ten, twenty, 
thirty, forty and so on turns may 
be obtained at will. Again, two switches may be used, 
one switch working by groups of ten or twenty, while the 
other switch cuts in one turn at a time. In this manner 
a relatively fine adjustment may be obtained. If 68 turns 
represents the proper adjustment, the first switch is turned 
to the -point connecting with 60 turns, and the second 
switch is turned to the eighth turn of wire. This arrange¬ 
ment is found in certain of the present-day receiving sets. 

Another means of varying the number of turns of an 
inductance coil is a sliding contact, which moves over the 
bared section of the wire. Such a device is termed a 
tuning coil, and is illustrated on page 117. Bare or 
insulated wire may be used on the tuning coil, so long as 
the adjacent turns are insulated one from the other, and 











RADIO FOR EVERYBODY 


113 


the proper contact is afforded between slider and wire. 

There are several ways of connecting the timing coil, 
a typical one being indicated in the accompanying diagram. 
It will be noted that the best arrangement calls for two 
sliding contacts or “sliders” as they are termed, and 

that in this instance the detector is 
really in a separate circuit from the 
antenna-ground circuit. It will be 
noted that this two-circuit arrange¬ 
ment is by far the most efficient, and 
in the most advanced types of receiv¬ 
ing equipment the two circuits are even 
separated from each other, so that 
there is no physical connection between 
the two. A small fixed condenser is 
placed across the telephone receiver, 
as indicated, in all crystal detector cir¬ 
cuits of this general category. 

The tuning coil, with its sliding con¬ 
tacts which do not always make per¬ 
fect contact, has more or less become 
obsolete. In its place we now find 
more delicate devices which give a finer 
adjustment, since the continuous-wave 
transmitters now widely employed in 
radio telephony and in radio telegraphy 
are exceedingly sharply tuned and even 
a fraction of a turn of inductance makes a considerable 
difference. So present practice favors another form of 
tuner known as the variometer. 

The variometer, which is shown in the accompanying 
illustration, comprises a fixed set of coils and a movable 
set of coils. As the knob of the variometer is turned, the 
relationship between the fixed and the movable coils is 
altered. When the variometer dial is set at 180, or what¬ 
ever may be the maximum dial reading, the coils are so 
arranged that the current will flow in the same direction 
in each set of coils, thus adding w^ave length to the circuit 



A two-slide tuning 
coil arranged for 
tuning the antenna- 
ground circuit and 
the closed detector 
circuit. 









RADIO FOR EVERYBODY 


114 

in which the variometer is placed. When the dial is set 
at 0, the two sets of coils are so arranged that the current 
will be flowing in opposite directions in both sets of coils, 
and the coils are then said to be in opposition or “bucking” 
each other. In that condition the inductance is greatly 
reduced, and the wave length is therefore at a minimum. 
Hence a considerable range of wave-length values may 
be obtained with very fine adjustment by the turning of 
the variometer knob. There are no loose contacts to bother 



The mebhanism of the variometer. This instrument consists of 
two sets of coils, one fixed set and one movable set. 


with, and the rotary action is far more convenient than 
the movement of sliders along a tuning coil. 

In the inexpensive receiving sets now being offered to 
the public, the tuning is effected by several methods. The 
lowest priced sets use merely an inductance with taps taken 
off at regular intervals and connected to the points of a 










RADIO FOR EVERYBODY 


115 


switch. This rough tuner is placed across the detector and 
telephone. Since the telephone offers too much resistance 
to the passage of high-frequency current to the detector, 
a small fixed condenser is placed across the telephone. 
Such a set, it must be evident, is satisfactory for short 
distances only, and cannot tune with any degree of ac¬ 
curacy so as to throw out undesirable stations and con¬ 
centrate on any given station. 
The sets selling for $20.00 or 
$25.00 are of a better grade, 
being provided with either a 
two-slide tuning coil, with the 
sliders arranged in the form 
of swinging arms so as to be 
operative by means of knobs, 
or a variometer. A crystal de¬ 
tector is supplied with such 
sets, as well as a pair of tele¬ 
phone receivers. A finer ad¬ 
justment may be obtained with 
such arrangements than can 
possibly be obtained with the 
simpler sets, and of course the 
results are accordingly ever so 
much better. Sets of this kind may receive radio-phone 
service over a distance of 25 miles or less, and with good 
conditions obtaining the range may be increased to 50 
miles. The Newark radio-phone broadcasting station re¬ 
ceived word some time ago that an amateur in Albany 
some 120 miles distant, was receiving the radio-phone 
music with a crystal detector, and this case is perhaps 
not so unusual. However, freak conditions are not to 
be depended upon, and when a definite distance must be 
spanned day after day, the receiving set should be con¬ 
sidered on the basis of minimum performance. Radio 
telegraph stations carry much farther than radio-phone, 
so that these same sets may receive radio telegraph sig¬ 
nals over 100 miles distant. 



Wiring scheme for a single 
variometer and a crystal de¬ 
tector. This arrangement pro¬ 
duces excellent results. 












116' 


RADIO FOR EVERYBODY 


The Mission of the Variable Condenser 

So far, we have only dealt with inductance as a means 
of tuning. Inductance makes for greater wave length: 
the more inductance is placed in a circuit, the greater the 
wave length. There is another device for varying wave 
length, and that is capacity, which was described in the 
first chapter. Capacity is presented by a condenser, which 



Outside and inside views of a variable condenser, showing its 
simple mechanism for varying capacity. 


may be of the fixed or variable kind. For the present we 
are interested in the variable kind. Various forms of 
variable, condenser are available, some with fixed and 
movable plates, the movable plate being hinged so that it 
can be moved toward or away from the fixed plate; others 
with a set of fixed plates and a set of movable plates that 
slide in grooves and pass in between the fixed plates with¬ 
out touching them; still others with a delicate means of 
increasing or decreasing the distance between a fixed and 
a movable plate; and, finally, the rotary type, in which 
there is a set of fixed plates and a set of rotary variable 
plates which glide in and out of the fixed set without 






RADIO FOR EVERYBODY 


117 


touching them. The maximum capacity is secured when 
the plates are nearest to each other or when the plates are 
entirely meshed, as the case may be. 

There is a simple rule that applies to the use of variable 
condensers in affecting wave length. When the condenser 
is in series, the wave length is reduced considerably, and 
fine variations may be obtained by adjusting the condenser. 
When the condenser is across or in parallel with induc¬ 
tance, it augments the wave 
length in proportion to the 
amount of capacity use. 

The value of the variable 
condenser comes in the fine 
adjustment of which it is 
capable. Thus the inductance 
units may be relatively crude, 
yet the variable condenser con¬ 
nected in series or in parallel with the inductance will 
serve as the finishing touch. It is much like a weighing 
operation, in which weights of several pounds are placed 
on the scale, while the delicate balancing is accomplished 
by a sliding beam weight. It is for this reason that in 
many radio receiving sets the inductance is varied in pretty 
big steps, while the finishing off, so to speak, is left to one 
or more variable condensers or even variometers, since 
the variometer is also capable of fine adjustment. 

The crystal detector is limited to short distances and 
to weak or moderate audibility in the telephone receivers. 
It is out of the question to ask for a loud-speaker in 
connection with a crystal detector. Again, a fairly large 
aerial must be used in connection with a crystal detector, 
unless one is situated within five to ten miles of a radio¬ 
phone broadcasting station, or within thirty miles of a 
radio telegraph station. Hence, sooner or later, and rather 
sooner than later, the radio enthusiast gets around to the 
vacuum tube detector, even though it does mean storage 
batteries and dry batteries, as well as more elaborate re¬ 
ceiving equipment. But the results are so much more 



A typical two-slide 
tuning- coil. 






118 


RADIO FOR EVERYBODY 


satisfactory with the vacuum tube detector that there is 
scarcely any comparison between such a set and the 
crystal type. 

The Vacuum Tube and What It Does 

The vacuum tube is the most interesting as well as the 
most useful device which has been developed during the 
progress of the radio art. Without going into the history 
of this device, it may be said that Edison originally discov¬ 
ered the peculiar behavior of an incandescent lamp fila¬ 
ment by inserting an extra wire in a lamp bulb. He 
discovered the fact that when a lamp filament is cold, no 
current can be passed across the vacuum between the 
filament and the extra wire or plate inserted in the vacuum. 
However, the moment the filament is brought up to incan¬ 
descence, a current can be passed across the vacuum gap 
between the filament and the plate; but the current can 
only be passed in one direction, since this device is a uni¬ 
directional or uni-lateral conductor of electricity. Thus 
the vacuum tube, as this device is called, may be used to 
rectify alternating current, since it allows the current to 
flow in one direction only and therefore converts alter¬ 
nating current into pulsating direct current. This prin¬ 
ciple is employed in certain storage battery recharging 
outfits, as well as in the detection of radio signals. 

What really takes place in the vacuum tube is subject 
to a good deal of theorizing, and bulky volumes have been 
prepared on the subject. It is not within the province of 
this book to deal with theories, but suffice it to state that 
the white hot filament gives off millions of infinitesimal 
electrically charged units known as electrons. These 
electrons travel from the filament to the relatively cool 
wire or plate placed in the vacuum tube, and thus form a 
bridge over which one-way traffic of outside electric cur¬ 
rent is permitted. Depending on the number of electrons, 
the bridge is of greater or less capacity, and therefore 
accommodates more or less traffic. 

Now in the present-day vacuum tube there is a traffic 


One of the several types of vacuum tubes used for detecting and amplifying purposes in receiving sets. 
Vacuum tubes for receiving purposes operate on a s'x-volt storage battery and a 22^-volt dry battery for 

the plate circuit. 




T3 


33 


Z 


O -i 


Z > 


n 


o 


[ft -t 





















120 


RADIO FOR EVERYBODY 


officer, so to speak, who decides how much traffic shall 
pass over the electronic bridge. It was Dr. Lee de Forest, 
the radio pioneer and inventor, who discovered how the 
traffic could be regulated, and introduced what we are 
pleased to call a traffic officer for the purpose of an ana¬ 
logous explanation. This third member, known as the 
grid, surrounds the filament and comes between it and 
the plate, so that the electrons must pass through the 
grid in order to reach the plate. Any charge which is 
impressed on the grid immediately affects the electronic 
flow, allowing a greater or less flow; and, consequently, 
the external current being passed over the electronic 
bridge, between the filament and the plate, is likewise 
altered by the grid charge—our little traffic officer, as 
it were. The grid consists of a piece of wire bent in zig 
zag form or again as a perfect helix or flattened helix, 
surrounding the filament and separating the latter from 
the plate. 

The vacuum tube is a most sensitive device. The slight¬ 
est charge impressed on the grid controls faithfully and 
instantly a rather strong current flowing between filament 
and plate. In this manner it becomes possible to control 
a strong current by means of a weak current. The incom¬ 
ing radio waves are led to the grid, where they serve to 
control the electronic flow, and this in turn controls the 
flow of current through the tube to the telephone receiv¬ 
ers. The arrangement is such that the radio waves are 
converted into audible sounds in the telephone receivers— 
loud, clear signals, such as never could be obtained with a 
crystal detector. 

The vacuum tube can be used for a great many differ¬ 
ent things. It is a rectifier of alternating current; that is, 
it converts alternating current of almost any frequency 
and of any strength within its capacity into direct current. 
It can, conversely, convert direct current into alternating 
current of a wide range of frequencies. It permits of 
controlling a powerful current with a weak current; this 
feature is the basis of the amplifier, since the character - 


RADIO FOR EVERYBODY 


121 


istics of a weak current are impressed on a current several 
times as powerful, therefore giving that much louder 
response in a telephone receiver. This characteristic is 
also the basis of the telephone repeaters, now employed 
in long-distance telephony. Vacuum tubes permit of re¬ 
building attenuated telephone currents at any desired in¬ 
terval of line, so that a greater distance may be spanned. 
The vacuum tube, of various capacities ranging from the 
small 5-watt tube to the large 250-watt tubes, can also 
be used for transmitting purposes, but that is another 
story which is left for later on. 

The “A” Battery and the “B” Battery 
of Vacuum Tubes 

Now the use of any vacuum tube involves a battery for 
heating the filament, which is the “A” battery but is more 
commonly referred to as the filament battery, as well as a 
high-voltage or “B” battery which serves to pass current 
across the electronic bridge between the filament and plate, 
when the filament is heated for the device to be actuated, 
whether it be a telephone receiver, an amplifier circuit, a 
recorder or other instrument. The filament battery, in the 
case of the more common vacuum tubes, is a 6-volt bat¬ 
tery although there are special vacuum tubes which oper¬ 
ate on lower voltages. Special tubes now available for 
all receiving sets operate on a single dry cell or about 
1.4 volts at the outside, and draw but Rj ampere of cur¬ 
rent. The usual vacuum tube, such as the Radiotron, 
requires close on to 6 volts and a trifle over 1 ampere. 
Another standard tube, known as the A-P tube, requires 
not more than 5 volts and about .7 ampere. This means 
that dry cells are quite extravagant in this connection, 
since with a drain of about one ampere, any dry cell 
will not last very long. If dry battery must be used, 
it is well to employ two sets of five cells each, the two 
sets being connected together. In other words, the five 
cells of each battery are arranged in series, with the 
carbon of one cell connected to the zinc of the other, 


122 


RADIO FOR EVERYBODY 


and then the end carbons of both sets are connected to¬ 
gether for one side of the combined battery, and the 
zincs of both sets are connected together for the other 
side of the combined battery. This virtually means a 
battery of .twice the life of a single battery, although the 
voltage remains the same. The name of this arrangement 
of batteries is series-parallel. 

Still, there is nothing that really takes the place of the 
storage battery in operating vacuum tubes. This is espe¬ 
cially true where more than one vacuum tube is being 
used, such as when using one or two stages of amplifica¬ 
tion, as is explained in the following chapter. The storage 
battery may be of any standard type, although since the 
heavy demand for radio equipment began some few 
months back, there have appeared several special storage 
batteries particularly intended for radio work. These 
storage batteries are characterized by all-rubber cases, 
eliminating the possibility of leakage from cell to ground 
or from cell to cell, and doing away with one of the most 
frequent causes of noisy sets. Furthermore, such batteries 
are of a smaller ampere-hour capacity than those used for 
automobile starting and lighting service, thus making them 
lower in cost and more convenient tc> handle and recharge. 

A storage battery must be recharged when it runs down. 
In a subsequent chapter we shall consider the care and 
recharging of the storage battery. Suffice it to state that 
where a radio set employs several vacuum tubes, so that 
the drain on the storage battery is considerable, it pays 
good dividends to install some form of recharging ap¬ 
paratus., In this manner the storage battery may be re¬ 
charged whenever necessary, at a minimum of expense 
and without losing valuable time. 

Aside from the storage battery for the filament, a “B” 
battery must be provided. This battery must be a high- 
voltage one. In the early days of vacuum tubes a number 
of flash-lamp batteries were connected together so as to 
obtain the necessary current, but today there are special 
dry “B” batteries put up in compact units of 22 ]/ 2 volts 


RADIO FOR EVERYBODY 


128 


each. These “B” battery units come in a small size and 
a large size. If the receiving set is to be used at regular 
intervals, it is the part of better judgment to buy the 
larger size. A single “B” battery unit is necessary for 
a vacuum tube detector circuit, and two units are neces¬ 
sary if an amplifier is also used with headsets; and three 
or four units if a loud-speaker is employed, as will be 
explained in the next chapter devoted to amplifier circuits. 

The dry “B” batteries come in two types, aside from 


GL 



Principle of vacuirm tube’s operation: GL—Grid leak; 
CC—condenser; F—filament; G—grid; P—plate; VT—vacuum 
tube; “A”—Storage battery for operating vacuum tube fila¬ 
ment; R—rheostat for filament current; “B”—high voltage 
“B” battery or plate battery, and telephones. 


the two sizes. There is the fixed voltage type, in which 
two leads or terminals give the full voltage of the battery, 
and there is a variable voltage type, in which lugs, binding 
posts, or holes and plugs permit of using a number of 
different voltages. The variable type is especially useful 
in using Certain types of vacuum tube with which the “B” 
voltage must be carefully adjusted. When it comes to 
amplifier tubes, the “B” voltage may be anything from 
45 volts up. 

There are also available special low-capacity high voltage 

























124 


RADIO FOR EVERYBODY 


storage batteries, which may be used in place of the dry 
battery units when a set is subjected to extensive use. 
Such storage batteries may be readily recharged and their 



Inexpensive receiving: set making use of a variometer tuner 
and a crystal detector. S<uch a set is good for a range of 
25 miles, perhaps a little more, when receiving radio-phone 

programs] 


operating cost must of necessity be lower than when using 
dry batteries, which, when discharged, are worthless and 
must be thrown away. 

Often the question is asked: Why is it not possible to 
use the usual lighting current for operating vacuum tubes. 



RADIO FOR'EVERYBODY 


125 


1 he fact of the matter is that we are dealing with delicate 
fluctuations in the vacuum tube. If the filament voltage 
should vary even in the slightest degree, the electronic 
flow would likewise vary and cause a corresponding noise 
in the telephone receivers. Therefore, for absolutely quiet 
operation it is necessary to employ a steady and positive 
flow of current such as can only be supplied by a battery. 
Lighting current, whether of the alternating or direct 
variety, could readily be reduced down to six volts, but in 
either case there is a distinct “hum” which would be con¬ 
stantly heard in the telephone receivers and which would 
drown out the delicate radio signals. Hence lighting cur¬ 
rent is out of the question. 

A Vacuum Tube for Every Purpose 

It is well to remember that all vacuum tubes are not 
identical, nor are they absolutely interchangeable. They 
may look alike if they are of the same size and kind, but 
there may be slight differences in internal dimensions and 
degree of vacuum or gas content which are not apparent 
even upon close examination. 

Thus the type now in most general use is classed as a 
soft or gas content tube and requires a critical adjustment 
of both the “B” or plate voltage and the “A” or filament 
current. Tubes of this type are extremely sensitive when 
properly adjusted. The variation of the filament current 
is accomplished by means of a variable resistance or rheo¬ 
stat placed in series with the filament lighting battery. In 
some receiving sets the rheostat may be calibrated in ohms 
or even in plain divisions, but in most sets it is not cali¬ 
brated at all, a simple arrow indicating in which direction 
to turn the knob in order to increase the voltage or 
brighten the filament. The “B” or plate voltage, on the 
other hand, is variable in steps of l l /2 volts, by means of 
a variable voltage “B” battery as already described. The 
proper terminal or lug or plug hole of the “B” battery is 
found by experiment, and no further adjustment is re¬ 
quired for a long time to come. The majority of vacuum 


126 


RADIO FOR EVERYBODY 


tube detectors operate best on “B” voltages between 16F> 
and 22y 2 , and this range is covered by the variations pro¬ 
vided on the various types of variable plate batteries. 


f - 


r 



VACUUM 

TUBE 


TUNING 
DIAL AND 
HANDLE 


filament 


A medium-priced receiving: set making: use of a special vacuum 
tube which operates on a single dry cell, instead of a 6-volt 

storagre battery. 


However, there is no harm in using a fixed voltage “B” 
battery, except that the best results are not likely to be 
obtained except if the tube should happen to be one that 
works best on 22]/ 2 volts. 





RADIO FOR EVERYBODY 


127 


Amplifier tubes, which look just like the detector tubes 
and cannot be told apart except by testing their electrical 
characteristics, are not critical in adjustment when com¬ 
pared with detector tubes, and they will operate success¬ 
fully on plate voltag-es of 40 to 80 volts. Where a detector 
and two-stage amplifier combination is used, three or four 
22E> volt units may be connected in series, and connections 
to the receiver are made in a manner which permits the 
use of the full voltage on the amplifier tubes, while a 
variable portion of the same battery is used for the de- 



Rear view of a simple receiving: set which makes use of a simple 
inductance and a variable condenser, as well as a crystal detector. 


tector tube. Where extremely loud signals are desired 
plate voltages of 100 or over may be used without damag¬ 
ing the amplifier tubes, but the use of this voltage increases 
tube noises and is therefore not desirable when receiving 
signals with the telephone head set. However, this infor¬ 
mation is only included here as part of the receiver prob¬ 
lem, and more will be said about amplifying tubes in the 
next chapter devoted exclusively to amplifiers. 




128 


RADIO FOR EVERYBODY 


A detector tube which does not prove to be critical as 
to plate voltage and filament current is usually defective. 
. A good detector tube will give greatly increased signal 
strength with a certain plate potential and filament bril- 



telephone 

JACK 


CRYSTAL DETECTOR 


VARIABLE INDUCTANCE 

CONDENSER CONTROL 


Front view of receiving set shown on page 127. The cabinet of 
this set is made of nietal instead of the usual wood. 


liancy. An amplifier tube which requires a critical plate 
voltage or filament current adjustment will not give satis¬ 
factory results as an amplifier. Tubes of this character 
will generally be found useful as detectors. In certain 
receiving sets which include an amplifier, it is sometimes 
















RADIO FOR EVERYBODY 


129 


found that amplifier tubes are recommended for use 
throughout, for the reason that the wiring provides for a 
common plate voltage and filament current adjustment. 
Such practice may simplify the construction and operation 
of the set, true, but from the standpoint of efficiency, it is 
mighty poor business. A soft or gassy tube, known as a 
detector tube, should be used for the detector, and a hard 
tube should be used for amplifying. These tubes, while 
they may look alike, are by no means interchangeable, 
except where the best results are not expected or de¬ 
manded. 

Having been introduced to the vacuum tube in a general 
way, we can now return to receiving sets once more. The 
vacuum tube can be used in place of a crystal detector 
in almost any circuit, and in such applications it will prove 
a considerable improvement over the latter. Then, by 
using special vacuum tube circuits, especially of the so- 
called regenerative variety, which will be described later 
on in this chapter, the sensitiveness of the vacuum tube is 
so much superior to the crystal detector as to make a 
comparison quite out of order. 

The wiring scheme already shown gives the fundamen¬ 
tals of vacuum tube hook-ups when used as a detector. 
It will be noted that a small fixed condenser and an ex¬ 
tremely high resistance, known as a grid leak, are placed 
in series with the tuner. Furthermore, the polarity of 
the connections is of utmost importance. 

Primary and Secondary Circuits and How They Are 

Coupled 

So far, the circuits have been of the simplest type, with 
a phvsical connection between the aerial-ground circuit 
and the closed circuit, known as the oscillating circuit, in 
which the detector is placed. Now for reasons which need 
not be explained here, since this work does not attempt 
to concern itself with the theories or the mathematics of 
radio but rather with the application of the results, many 
sets make use of distinct aerial-ground and oscillating 


130 


RADIO FOR EVERYBODY 




Loose-coupler of the old type 
which has now become more 
or less obsolete. 


circuits, with no physical connection between them. Trans¬ 
ference of energy between the former and the latter is 
effected by means of two windings which are brought into 
more or less close inductive relation. In one form these 
windings are known as a loose-coupler, in another they 

form a vario-coupler, still an¬ 
other arrangement calls for 
compact coils held in hinged 
holders so that they may be 
swung towards or away from 
each other. 

The loose-coupler is the 
forerunner of the vario- 
coupler and the compact coil 
arrangement. It consists of a 
large tube on which are wound 
many turns of wire, which is 
the primary and is connected with the antenna and the 
ground, and a smaller tube, which slides in and out of the 
large tube and is wound with many turns of wire. Some 
means, such as a slider or a multi-point switch, is generally 
employed to vary the number 
of active turns in both the pri¬ 
mary and secondary of the loose 
coupler. 

In keeping with modern prac¬ 
tice, which has done away with 
sliding arrangements in favor 
of rotary adjustments, the vario- 
coupler has become the stand¬ 
ard device for coupling the 
primary and secondary circuits 
of a receiving set. The vario- 

coupler has a tube wound with Lk r ^" C the Ple pia«e W Sf ic the h <3d 
many turns of wire, forming t ^* )e loose-coupler. 

the primary or antenna-ground circuit, and a wooden 
ball or composition frame, which is mounted on a rotable 
shaft and is also wound with many turns of wire to form 











RADIO FOR EVERYBODY 


131 


FT 


p 

G 

J L 

1 

Z FC 


lc 




How a loose-coupler or vario- 
coupler is introduced in a crystal 
receiving set. In this instance 
the primary is adjustable. 

ployed. The radio amateur 
soon learns to arrange and re- 
* arrange his receiving equip¬ 
ment until he obtains the best 
results—if he is ever satisfied. 


Inductance in Small Packages 


the secondary or the oscillating 
circuit member. 

The accompanying diagrams 
indicate better than words 
how the loose-coupler, 
vario-coupler, or inductance 
coil mounting may be em¬ 
ployed in connection with a 
vacuum tube or a crystal 
detector. Obviously the 
vacuum tube is to be used 
wherever possible. There 
are also given several cir¬ 
cuits in which fixed in¬ 
ductance units, vario-meters 
and condensers 
A A 


are em- 


The tuning coil has more or less 
become obsolete, and in its place 
we find more compact forms of in¬ 
ductance. One of these later-day 
forms is a single layer of wire 
wound on a tube, after the fashion 
of 'the tuning coil, but having a mul¬ 
ti-point switch connected with vari¬ 
ous numbers of turns, in- Using a loose-coupler or vario- 
c +po A o clirl^r TVi^n coupler in connection with a 

steaa oi a snaer. i nen mere variometer and a variable con- 

are the compact inductance denser for increasing or deereas- 
• i , -r^ ing the antenna circuit wave 

coils, such as the Duo- length. 

















132 


RADIO FOR EVERYBODY 


Lateral and the Honeycomb types, which, while fixed as 
regards their wave length values, are used interchangeably 
so that the operator can readily shift from one coil to 
another and* thus vary the wave length in big steps, de¬ 
pending on a variometer or a variable condenser for the 
finer tuning. 

Second only to the development of the vacuum tube, the 
concentrated inductance has marked a new era in radio. 
Prior to the war there were in general use the huge, bulky, 
single-layer inductance coils then so closely identified with 

long-wave recep¬ 
tion. Compact re¬ 
ceiving sets, sim- 
p 1 e adjustments, 
and the neatness 
that goes with 
small units, were 
not to be thought 
of because of the 
bulkiness of the 
inductance then 
employed. 

The demand for 
compactness and 
simplicity, to¬ 
gether with the 
far greater effi¬ 
ciency and prac¬ 
ticability, on the 
part of the war¬ 
ring nations, called for a radical change in inductance de¬ 
signs. As a consequence, so-called bank-wound coils were 
employed to an increasing extent, followed soon after by 
the present types of concentrated inductances. Today 
practically all receiving sets with a long-wave capacity 
are provided with these compact inductance units since a 
long wave length can be obtained in a very small space. 

Special mountings have come into use for these compact 



One style of mounting: which takes two or 
three compact inductance coils for a loose- 
coupler, and tickler coil combination when 
using: a regenerative circuit. 






RADIO FOR EVERYBODY 


13S 


inductance coils. The usual method is to mount the coils 
on a block by means of a fiber band which passes around 
the coil to hold it in place. The block, in turn, is provided 
with bayonet plugs so that it can be readily plugged into 
a circuit. A loose-coupler arrangement is effected by 
means of a stand which permits of moving the coils 
towards or away from each other, and, in some cases, even 
turning one of the coils from the vertical to the horizontal 
position. 

Another form of compact inductance is known as the 
spider-web inductance. This consists of a sheet of in¬ 
sulating material in which radial slots have been cut, and 
the wire is wound spirally in and out of these slots, so 
as to make a flat or pancake inductance unit. Such 
inductance units can be used as a loose-coupler by having 
one fixed and the other hinged. 

The Question of Telephone Receivers 

Little or nothing has so far been said regarding the 
telephone receivers, yet here is an important member of 
any receiving set. In fact, no matter how elaborate a 
receiving set may be, if the receivers are not of the best 
available type, the results are not as good as they might be. 

Radio telephone receivers are not just ordinary tele¬ 
phone instruments. They are far more sensitive than 
anything which is ever used in regular wire telephony. 
First of all, they are constructed with the utmost care; 
secondly, they have windings of very fine wire, as com¬ 
pared with 'the relatively large wire used in the ordinary 
telephone receiver. Thirdly, the diaphragm of the usual 
wireless receiver is far thinner and therefore more delicate 
than that used in the ordinary telephone receiver. 
Fourthly, in certain types of wireless receivers the two 
receivers of a head set are matched in tone, so that both 
ears receive precisely the same sounds. This feature 
makes for the utmost response on the part of the ears, 
and therefore the best signals. 

No matter how inexpensive a receiving set may be, it 


134 


RADIO FOR EVERYBODY 


is poor business to economize on the telephone receivers; 
for it is a fact that a receiving set is no better than its 
telephone receivers. The telephone receivers, after all, are 
the final link in the chain of reception; they comprise the 
agency which actually conveys the radio signals or music 
or what not to the operator’s ears, and as such they can 
add to or detract from the receiving set as a whole. 



ADJUSTABLE INDUCTANCE 
COIL 

WINOOW FOR DETECTOR TUBES 

WINDOWS FOR AMPLIFIER 
TUBES 


PRIMARY 
CONDENSER 


SECONDARY 

CON0ENSER 


PLUG FOR 

TELEPHONES 


Receiving set in which three compact inductance coils, adjusta¬ 
bly mounted on top of cabinet, permit of variable coupling and 
regenerative action. The unit at right is the vacuum tube de¬ 
tector and two-stage amplifier. 


Of radio telephone receivers, there are various types 
and special merits are claimed for each type, as might 
well be expected. However, there is one fact that applies 
to all types, and that is the care with which a really good 
receiver must' be constructed. That is why the better 
offerings cost considerably more than others; and it will 
generally be found that the better offerings are well worth 
the extra cost. If the radio amateur does not feel he can 
afford the better kind of telephone receivers, he can at 
least start with an inexpensive pair, and later on go to 
the better kind, experiencing thereby considerable pleasure 





RADIO FOR EVERYBODY 


135 


in the increased range and clearer signals or telephone 
messages which he obtains with his receiving equipment. 

Certain types of receivers have been carefully matched 
for tone and pitch, and respond loudly to signals over a 
wide range of frequencies, especially those of high pitch, 
thus permitting reception that would not be possible with 
inferior head sets that do not respond to signals of high 
frequency. Other types have two solenoids wound on the 
pole pieces of a laminated permanent magnet which acts 
upon an iron reed fastened to a conical aluminum 
diaphragm. The reed is adjustable and, therefore, the 



FILAMENT 

RHEOSTAT 


TELEPHONE PLUG 


OM pact INOUCTANCE COfL 
TUNING DIAL 
VACUUM TUBE. 


HEAD PHONES 


Receiving set making use of compact inductance coils for rapidly 
changing the wave length range in erg steps. The unit at 
right is the vacuum tube detector. 


reed note can be made identically the same in both ear 
pieces to coincide with the spark frequency of incoming 
signals or what is known as the beat frequency. An ad¬ 
justment screw is mounted on the back of each receiver 
case and is designed so that excess adjustment cannot be 
made. The diaphragm is of unusual design, being of a 
conical shape with greater thickness toward the center. 
This design is said to result in improved reproduction. 




136 


RADIO FOR EVERYBODY 


There is still another type of wireless telephone receiver 
in which a solenoid winding is mounted in such a manner 
with relation to the long permanent magnet within the 



A single circuit tuner making use of a variometer and a variable 
condenser, as well as a tickler for regenerative effects. The 
general tuning is done with the first handle, the fine tuning 
with the lower left-hand knob, and the regenerative effect is 
controlled with the lower right-hand knob. 


case as to actuate an armature which connects with a mica 
diaphragm. The slightest current variations throughout 





RADIO FOR EVERYBODY 


137 


the solenoid windings will actuate the armature which in 
turn vibrates the diaphragm. 

With all receiving sets, whether of the crystal or the 
vacuum tube type, it is generally impossible to use a loud- 



Companion unit to tuner shown on preceding page. This unit is 
the vacuum tube detector and two-stage amplifier. The two knobs 
are the rheostat controls for the detector and amplifier tube fila¬ 
ments. The telephone plug may be inserted in one of three holes 
or jacks, if detector only, one stage or two stages of amplifica¬ 
tion are desired. 

speaking telephone—an instrument equipped with a horn 
that projects loud sounds throughout a large room, thus 
making the use of telephone head sets unnecessary. A 
loud-speaker must be operated by means of an amplifier, 







138 


RADIO FOR EVERYBODY 


and this phase of radio reception will be described in the 
next chapter. It occasionally happens that nearby trans¬ 
mitters are received so loudly that they may be heard 
some distance away from the telephone receivers. Under 
such circumstances, it is obviously possible to attach a 



Regenerative set making use of tickler coil. P—primary of 
vario-coupler; TIC—tickler coil; VC1—variable condenser for 
varying antenna-ground wave length; VC2—variable con¬ 
denser for varying secondary of vario-coupler; GJL—grid 
leak; GC—grid condenser; VT—vacuum tube detector; B— 
high voltage or plate battery; FC—fixed condenser; T— 
’phones. The dotted line indicates how wiring w T ould run 
for an ordinary, non-regenerative set. 


horn to a telephone receiver and thus have an improvised 
loud speaker, but this is certainly the rare exception rather 
than the general rule. 

Regenerative Reception or Self Amplification 

So far, the various receiving layouts or hook-ups have 
brought the radio frequency energy right to the detector, 
which in turn rectified it and passed it on to the telephone 
receivers. Now if the energy which is about to be passed 
on to the telephones is partly re-impressed on the grid 
of the vacuum tube, it will add materially to the voltage 
of the incoming signal. This will naturally give a greater 
charge on the grid, and consequently a greater variation 



























RADIO FOR EVERYBODY 139' 

of plate current, which in turn means louder signals. In 
this manner the sensitiveness of the vacuum tube is greatly 
increased; indeed, it is operating as a detector and an 
amplifier combined. This practice is known as the regen¬ 
erative or feed-back reception. 

But how is the plate energy re-impressed on the detec¬ 
tor? There are two methods in general use for obtaining 
the regenerative effect. The first makes use of what is 
known as the tickler—an extra coil which is brought near 
the inductance or winding of the detector or oscillating 
circuit. Thus the simplest type of regenerative receiver 
consists not of two compact inductance coils but of three 
coils, adjustably mounted, as shown in the diagram on 



variometer; GL—grid leak; VC2—variable condenser as grid 
condenser; VT—vacuum tube detector; V2—plate variometer 
for feed back; FC—fixed condenser; T—telephones; “B”— 
high voltage or plate battery; R—filament rheostat; R1— 
high voltage battery rheostat. 


page 138. The first coil is the primary, connected with 
the aerial-ground circuit as already mentioned, and the 
second is the secondary, connected with the detector. The 
third is the tickler, and is connected in the plate circuit, 
as indicated by “TIC” in the wiring diagram. The 
adjustment between the tickler coil and the secondary coil 
is of great importance, for the regenerative effect must 



























MO 


RADIO FOR EVERYBODY 


often be regulated to obtain the best results, as will be 
explained in the chapter on operating radio stations. 

The tickler coil also comes in handy when receiving un¬ 
damped signals, which, as explained in our first chapter, do 
not affect the simpler types of receiving sets and therefore 
cannot be detected. With the tickler it becomes possible 
to adjust the coils in such a manner that the detector 
begins to oscillate; in other words, it is generating high 
frequency current on its own account. If this high fre¬ 
quency current is modified until it varies but slightly from 
the frequency of the incoming radio wave, then there will 
be heard in the telephone receivers the difference between 
the two frequencies. For instance, if the incoming radio 
wave is 100,000 cycles frequency, the detector circuit 
can be adjusted to 102,000 cycles frequency, and there 
will then be heard in the telephone receivers a note of 
2,000 cycles, which is clearly audible. The note detected 
is known as the “beats,” and can be varied in tone accord¬ 
ing to the adjustment of the circuit and the incoming 
frequency. Obviously, this method gives almost any note 
desired, therefore the transmitting stations received in 
this manner do not have a characteristic note such as is 
obtained by other methods of transmission and reception. 

Another method of receiving undamped waves, such as 
are sent out by arc stations, is to employ a “tikker.” Such 
practice is only resorted to with a plain receiving set, such 
as one using a crystal detector, with no provision for set¬ 
ting up local oscillations so as to obtain “beats.” This 
is merely some means of breaking up the incoming high* 
frequency wave energy so that it becomes audible and 
therefore can be detected in the telephone receiver. One 
method is to use a small pulley mounted on an electric 
motor, and to have a wire resting in the groove of the 
pulley. When undamped waves or CW signals, as they 
are called, come through such an arrangement, they are 
received in the form of short or long scratchy sounds, 
because of the tikker’s interruptions. However, a tikker 
is in reality an imperfect contact and as such it takes away 
from the strength of the incoming undamped or CW 


RADIO FOR EVERYBODY 


141 


signals. Therefore the regenerative arrangement is to 
be preferred. 

Two other methods in general use for regenerative 
reception are shown in the accompanying diagrams. It 
will be noted that instead of a tickler coil, use is made 
of a variometer in the plate circuit. This variometer 
serves to tune and feed back into the grid the added 
voltage of the plate circuit. 

All regenerative sets are delicate to operate, for the 
regenerative effect gives rise to all kinds of noises in the 



to the babel of sounds that might be expected in a monkey 
house riot. The operation of such a set is considerably 
more involved than the plain receiving equipment, but on 
the other hand the self-amplifying feature greatly adds to 
the results. Furthermore, it is necessary to use metallic 




























U2 


RADIO FOR EVERYBODY 


shields between the operator and the components of the 
regenerative set, since the capacity of the body of the 
operator materially affects the delicate adjustments of the 
regenerative set. Most of the better regenerative instru¬ 
ments are provided with metallic shields inside the cabi¬ 
nets, so as to reduce the body capacity trouble to a mini¬ 
mum. In other instruments the dials are of metal and 
are grounded to act as shields. 



A—filament battery; R—filament rheostat; It—“B” or plate 
battery; FC—fixed condenser; T—telephones; V2—plate or 
“feed-back" variometer; G—ground. 

t 

There is virtually no end to the different arrangements 
which can be followed in receiving radio signals. The 
wiring diagrams shown in the foregoing pages are only 
intended as a preliminary guide, and are offered as sug¬ 
gestions to the beginner. As one becomes more proficient 
and versed in the radio art, one soon learns other arrange¬ 
ments which may prove more interesting and efficient. 


I 























Chapter V. 


OPERATING THE RADIO RECEIVING 
SET AND MASTERING THE 
TELEGRAPH CODE 


T HE day may arrive when the radio receiving sets, 
capable of receiving clear, loud music from distant 
points, will be reduced to the simplicity of the phono¬ 
graph. For the present, however, simplicity exists only 
in the inexpensive receiving sets, which are intended for 
the reception of radio telephone and telegraph signals at 
short range. When it comes to receiving sets for ranges 
of 25 miles or more, good results can only be obtained 
with elaborate apparatus. And the more elaborate the 
apparatus becomes, the greater the care and skill required 
for its successful operation. 

Take the simple receiving sets, for example. There 
is little or nothing to master in the way of operation. Such 
sets generally have a multi-point switch for controlling 
the wave length, and a crystal detector. The crystal de¬ 
tector must be accurately adjusted for the utmost sen¬ 
sitiveness, and this requires a little care. The crystal used 
in such a detector is not of uniform sensitiveness through¬ 
out, hence the little metal point or the fine wire, making 
contact with the crystal, must be shifted about until a 
sensitive $pot is obtained. 

At almost any hour of the day there is a radio telegraph 
station working within range of the simplest receiving 
set, unless the latter happens to be located in some very 
remote spot. In that event, the simple set should not 


RADIO FOR EVERYBODY 


744 

have been selected in the first .place, for its radio telegraph 
range, as a rule, is certainly no more than 50 to 100 miles, 
while its radio-phone range is less than 25 miles. In this 
connection it is well to point out that many persons have 
been and are buying little $15.00 receiving sets for use in 
some remote part of Canada or Texas or Montana or 
some other section far removed from the existing radio¬ 
phone broadcasting stations, and are surprised and bitterly 
disappointed at not receiving the music and talks which 
they have read so much about. Most radio manufacturers 
are careful not to sell their instruments under such circum¬ 
stances, for they realize that disappointments of this 
nature only result in giving the public a wrong impres¬ 
sion of radio, which may persist despite all future efforts 
to explain why they failed in their first attempt. 

At any rate, if a person is located well within the range 
of radio telegraph and radio telephone stations, the crystal 
detector can be readily adjusted. While listening with 
the telephone receivers, the operator shifts the little point 
or wire about on the crystal. If there is a radio telephone 
or telegraph station working within range, one soon hears 
the music or talk or again the short and long buzzes, as 
the case may be. There may be no trasmitter operating 
at the time, and no sounds will be heard. For this reason, 
it is sometimes necessary to use some simple form of 
tester to determine the sensitiveness of the detector, 
without depending on actual signals. 

Is the Crystal Detector Sensitive? 

When the crystal detector is adjusted properly, it 
should respond to disturbances other than actual radio 
waves. Thus in the city, where there are electric light 
wires, telephone lines, trolley cars, elevators and other 
electrical appliances and machinery, the detector should 
respond to the electromagnetic waves given off by elec¬ 
trical machinery of all kinds within range. In other 
words, if the detector remains absolutely silent, then it is 
evident that no sensitive spot has been found; but if it 
causes clicks, scratchy sounds, buzzes and other noises to 


RADIO FOR EVERYBODY 


145 



be heard in the telephone receiver, then it may be taken 
for granted that the detector is satisfactorily adjusted. 
Sometimes the sensitiveness may be tested by turning on 
and off a nearby electric lamp. This should produce a 
loud click in the telephone receiver. However, if a hum 
is neard, this should not be considered as an indication of 
th< sensitiveness of the detector adjustment. Indeed, the 

hum is caused by what is 
known as induction, given off 
by an alternating current line. 
This hum may be picked up 
when the point or wire is not 
even pressing on the crystal; 
so that, far from indicating a 


A combination receiving- and CW transmitting set of the 
inter-panel type, with the various units standardized so that 
they can be assembled to form any desired arrangement for 

the amateur station. 


sensitive detector, it should indicate that the detector 
members are not even in proper contact. 

For those desirous of making sure of their crystal 
detector adjustment, it is perhaps best to use what is 
known as the buzzer test. This calls for a small buzzer, 
such as is used in bell circuits. The buzzer is connected 
in the usual manner with a push button and cell of dry 
battery, but a wire is brought from one side of the buzzer 
interrupter to the ground lead of the receiving set to be 
tested. Then, when the buzzer is operated, the electro- 



146 


RADIO FOR EVERYBODY 


magnetic waves given off by the buzzer interrupter are 
impressed on the radio receiving set and the detector can 
be adjusted for sensitiveness in the same manner as 
though the operator were listening for a radio transmitter. 
The buzzer test is still used in some forms of elaborate 
receiving sets which include a crystal detector, for the 
reason that it serves as a positive indication of the sen¬ 
sitiveness of the crystal detector. 

For the general run of radio receiving, however, a 
buzzer test is hardly necessary. If a crystal detector set 
is being used well within the range at which such appar¬ 
atus is Operative, the detector can soon be adjusted while 
listening to actual transmitters. However, if the crystal 
detector receiving set is being used beyond the usual range, 
then it may be necessary to use some form of buzzer test 
in order to make certain that the detector is adjusted to 
the utmost sensitiveness. 

As for the tuning of simple sets, there is little to be 
said. The switch handle or the tuning handle is moved 
about until the desired transmitter is intercepted. With 
any aerial up to 150 feet long, the simple set should give 
excellent results. However, in the event that the aerial 
is over 150 feet long, or that a long lead-in wire has had 
to be used in order to connect the antenna with the receiv¬ 
ing set, it may so happen that the natural wave length 
of the antenna circuit is greater than that of the desired 
radio-phone or radio telegraph waves. In such instances 
a fixed or variable condenser should be placed in series 
with the antenna or the ground, thus reducing the wave 
length. 

While it is desirable to keep receiving sets as simple 
as possible, especially where laymen who will always be 
laymen are concerned, good results, more particularly at 
a considerable distance from the transmission station, 
can only be obtained with fine tuning facilities. Fortu¬ 
nately, one soon becomes used to tuning a receiving set, 
no matter how many handles may be involved in the 
tuning operation. Even with a tuning coil, the operator 
soon learns just where to place the single o-r double sliders 


RADIO FOR EVERYBODY 


147 


in order to pick up any given radio telephone or radio 
telegraph station. With a loose-coupler tuner, the oper- 



Nothing is simpler than erecting: the antenna for receiving: pur¬ 
poses. A single wire, with insulators at either end, is run 
between the house and a barn, tree, or clothes pole. Then a 
tap is taken off’ the near end of the antenna and brought into 
the house. This is known as the lead-in. 







148 


RADIO FOR EVERYBODY 



It is best to pass all wires through porcelain tubes when they 
enter the house, as shown here, even though the wires may be 
heavily insulated. It is an additional precaution well worth taking. 

ator soon learns how to adjust the primary and secondary 
circuits, and how much coupling to use. With condensers 
or variometers, the operator becomes familiar with the 
adjustments of the various dials for picking up any desired 
transmitter. Indeed, some instruments are provided with 
dials that have plain subdivisions, without numbers of any 
kind, or even with plain pointers and blank backgrounds; 
yet the operator soon learns just where to place the dials 
or pointers in order to obtain the desired results. 

At first, the operation of a radio receiving set is apt to 
be a little complicated and possibly disappointing, for the 
reason that the operator may not obtain the best results 
immediately. But at the end of an hour or two the oper¬ 
ator readily masters the various adjustments and knows 





RADIO FOR EVERYBODY 


149 


just where to place the dials and pointers in order to pick 
up the transmitters which he wants to listen in on. Fur¬ 
thermore, it is interesting to note that any extensive 
change in the antenna varies the relative adjustments of 
the receiving set. Thus if the operator is accustomed to 
a given antenna, the changing of the proportions of that 
antenna or its height will upset the previous tuning values 
and the operator will have to learn his adjustments all 
over again. However, much of the fun that is afforded 
by radio comes in learning how to tune the receiving set 
and in searching for new transmitters. 

Installing the Receiving Set 

In a way, the few pointers regarding the installation 
of the receiving set should come ahead of the foregoing 


The vacuum gap type of lightning arrester is widely employed 
for receiving stations only. It is automatic in its operation, 
being always ready for action, no matter whether the receiving 

set is being used or not. 






150 


RADIO FOR EVERYBODY 


data on the operation of the simple receiving sets. But 
as a matter of fact one need pay little attention to the 
installation of the simple sets, for the reason that their 
simplicity limits their efficiency, so that the finer details 
of installation hardly apply to them. When it comes to 
elaborate vacuum tube receiving sets, it may be well to 
give a little thought to the installation for the purpose 
of obtaining the utmost efficiency. 

To begin with, the receiving apparatus should be so 
placed as to permit of the shortest possible leads from the 
receiver to the point where the antenna lead-in enters the 
building. Sufficient space should be provided between 
the instrument and the edge of the desk or table to allow 
the operator to rest his forearm when adjusting the con¬ 
trols. Right here we can draw a comparison with the 
simpler sets, which have a single knob or perhaps two 
knobs on top of the case or on the side, the adjustment 
of which does not have to be so delicate as to call for the 
resting of the forearm. In the case of elaborate vacuum 
tube apparatus, however, the turning of a knob a hair's 
breadth may make for all the difference between distorted 
music or talk, or perfect reception. 

The antenna lead from the lightning switch should pass 
through the wall or window within a porcelain tube or 
special lead-in insulator. We have already read of the 
board which can be placed in the window frame so that 
the window may be raised or lowered without interfering 
with the lead-in passing through the board placed at the 
top or the bottom of the window frame. If the lead-in 
is not insulated itself—heavily insulated wire is generally 
employed for this purpose—then it should be supported 
away from the walls by means of small wall insulators. 
The ground connection lead does not require any special 
insulation; ordinary No. 14 rubber covered copper wire is 
well adapted to this purpose. 

From Bed Springs to Fire Escapes and to Loops 

There are times when one cannot install the usual type 
of antenna for receiving purposes. In such an event one 


RADIO FOR EVERYBODY 


151 



Too much pains cannot be taken with the ground connection. 
The ground may seem simple enough—and it is; but one should 
use a good ground clamp whenever possible, and connect it 
with the cold water pipe for best results, as shown here. 

need not give up the idea of radio, for almost anything 
will serve for an antenna especially when receiving from 
nearby stations. Excellent results may. be obtained with 
a piece of wire about 40 feet long, just strung back and 








152 


RADIO FOR EVERYBODY 


forth in a room or placed behind the picture moulding 
so as to be out of sight. We know of a man who 
uses an antenna for receiving from the Newark broad¬ 
casting station at a distance of 250 miles, and, on oc¬ 
casion, from Pittsburgh, some 650 miles away. The same 
man receives the signals of Nauen, Bordeaux, and other 
European high power stations with the same antenna. 

The usual fire escapes found in 



Simple vacuum tube hook-up for use with a loop antenna. 
Note that VC is a variable condenser; GL—grid leak; V— 
variometer acting as the “feed back” inductance; T—tele¬ 
phone receivers; 15—“15” or plate battery; FC—fixed con¬ 
denser; R—rheostat for filament current; A—filament battery. 
This arrangement will operate over short distances. For 
greater range a radio frequency amplifier must be used 

scraping the paint ofif clean in order to make a good con¬ 
nection with the metal. Sometimes a gas pipe makes an 
excellent antenna, while the water pipe is used for the 
ground. If nothing better presents itself, a metal bed¬ 
stead or bed spring serves as an antenna, with good re¬ 
sults. Indeed, the problem of the antenna need never 





























RADIO FOR EVERYBODY 


153 


trouble the radio devotee, for the reason that with the 
sensitive receiving equipment of today most anything will 
serve as an antenna when working over short distances. 

Then we have the loop, which takes the place of antenna 
and ground connection. The loop is connected in the 
same way as would be the secondary of a vario-coupler or 
loose-coupler. A condenser is placed across the loop 
terminals so as to vary the wave length. A typical loop 
hookup is given in the accompanying wiring diagram, 
which, it will be noted, makes use of a plate variometer 
as the feed-back in order to obtain regenerative action. 
A loop outfit of this kind gives good results over reason¬ 
able distances, although it does not cover the same dis¬ 
tance as would the same equipment when used with a 
good antenna. However, during the summer months 
when there are many lightning storms and when static is 
at its very worst, the loop presents an interesting means 
of reception. To begin with, the loop is safe from light¬ 
ning even at the height of a lightning storm, since it 
can be used indoors. Furthermore, the loop does not 
pick up static as does the usual antenna, for the reason 
that it does not make use of a ground connection. But 
it is well to remember that a loop intercepts but a small 
portion of the usual energy intercepted by a good antenna. 
Therefore, for best results a radio frequency amplifier, 
such as described in the chapter on amplifiers, should be 
employed in order to build up the wave energy intercepted. 
The loop is a directional receiver—it receives best when 
pointed end on towards the transmitter. Many inter¬ 
esting experiments can be performed with a loop. 

Elaborate receiving sets presuppose the use of the 
vacuum tube detector, for no really efficient radio reception 
at considerable distances can be obtained without this form 
of detector. With the introduction of the vacuum tube, 
however, the operation of a receiving set becomes a trifle 
more complicated than with the crystal detector, for while 
the latter does not give forth sounds of its own and is 
virtually silent except for the wireless telegraph and radio 
telephone waves, the vacuum tube creates plenty of noises 


154: 


RADIO FOR EVERYBODY 


of its own in addition to the desired signals and telephone 
messages and music. A person passing from a simple 
crystal set to a vacuum tube set may be disappointed at 
first, because the vacuum tube makes so much noise and 
has to be tamed occasionally, so to speak, in order to 
subdue it, especially when using the utmost regenerative 
action. But when the vacuum tube is once adjusted prop¬ 
erly, the clarity of the received messages or music, together 
with the strength of such messages or music, is so far 
ahead of the crystal detector as to make a comparison a 
sheer waste of time. 

Vacuum tubes should not be put in place until it has 
been ascertained that all battery connections have been 
correctly made. This will avoid the accidental destruction 
of the tubes. The tubes, which cost upwards of $5.00 
each, may be burnt out just as any electric lamp can be 
burnt out by applying excessive voltage on the filament. 
There are on the market little fuses which fit on the con¬ 
necting pins of any vacuum tube, and it may be the part of 
good judgment to provide one’s vacuum tubes with these 
little fuses as a measure of protection. At any rate, if all 
battery connections are checked over and found to be 
correct, it will avoid the accidental destruction of the 
tubes whether fuses are provided or not. 

The filament lighting battery, which is generally a 
storage battery, may be placed on the floor directly be¬ 
neath the apparatus and the wires connecting this battery 
with the apparatus should be at least No. 14 B. & S. copper 
wire, properly insulated. Dry battery, consisting of four 
cells, may be used with a single standard detector tube, 
but it is expensive practice and not very satisfactory. 

The condition of a storage battery may be tested by 
means of a hydrometer or a voltmeter. The hydrometer 
is an instrument which measures the specific gravity of 
the storage battery liquid or electrolyte, to give it the 
technical name. The cap or plug of each cell of storage 
battery is removed, and the hydrometer tube is inserted 
in each cell. Squeezing the rubber bulb of the hydrometer, 


RADIO FOR EVERYBODY 155 

and then releasing it, causes the electrolyte to rise in the 
glass tube of the hydrometer. The specific gravity can be 



Large loop antenna employed for the reception of trans-Atlantic 
messages by a New York newspaper. The loop is mounted so 
that it can be orientated or pointed towards the transmitting 

station. 


































































































156 


RADIO FOR EVERYBODY 


readily determined, and the relative charge of the cell ob¬ 
tained in this manner, by means of the bob or float. 

One popular form of hydrometer now on the market 
has three colored balls in the glass tube, instead of the 
usual bob with buckshot, which may be a little confusing 
to the layman. If all three balls of this new hydrometer 
stay up when the electrolyte is introduced, the battery 
is fully charged. If the white ball goes down or sinks, the 
battery is all right. If the green goes down, the charge 
is lean. If the red goes down, the charge is dead. This 
hydrometer affords a simple test for any storage battery. 

When using a voltmeter, it is necessary to have an 



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The construction of a “B” battery, showing; the separate cells, 
the waterproof partitions, the special insulation, the terminals, 
and the method of sealing the entire battery. 


instrument especially intended for the purpose, which 
measures from 0 to 3 volts, or 0 to 5 volts. The fully 
charged cell registers 2.2 volts. When the voltage drops 
to 1.8 volts per cell, the battery should be recharged. To 
allow the cell to drop below 1.7 volts is bad practice, for 
it hastens the wear and tear on the battery. 

Storage batteries are rated in ampere hours. Generally 
speaking, a 20-ampere-hour battery will furnish a current 
of 1 ampere for 20 hours, 5 amperes for four hours, and 









RADIO FOR EVERYBODY 


157 


so on. If a vacuum tube detector alone is being used, 
then a 20-ampere-hour capacity is sufficient. If ampli¬ 
fiers are employed, a 60-ampere-hour storage battery 
should be used. Vacuum tubes of the standard type re¬ 
quire about 1 ampere each, so that a 60-ampere-hour bat¬ 
tery should operate a receiving set of detector and two- 
step amplifier for about 20 hours, after which the battery 
must be recharged. 

Storage batteries may be recharged by means of a simple 
home recharger, or can be sent to a nearby garage or 
lottery service station. The home recharging sets are 
designed for direct or alternating currents. The latter 
class are of two general types, namely, the vibrating reed 
type and the vacuum tube rectifying type. The former 
has a vibrating reed which rectifies the alternating current 
and steps it down to a suitable charging current. The 
vacuum tube rectifying type has a special vacuum tube 
which rectifies the current. A transformer steps down 
the current. The author has used a vibrating reed re¬ 
charger with excellent results, and at a cost of but a few 
cents for each charge. In fact, in the long run a recharg¬ 
ing set pays for itself many times over, since the regular 
price of recharging a battery is 50 cents to $1.00 in most 
service stations, while the cost with a home recharging 
set is a matter of 10 to 20 cents, depending on the size of 
the battery and the length of charge. 

The plate batteries, which are the high voltage batteries, 
will be most accessible if placed directly back of the 
receiver so that the wires can be readily brought to the 
proper binding posts of the receiver and amplifier units. 
Of late a number of B storage batteries have appeared 
on the market. It is claimed that the storage battery type 
is more economical in the long run than the dry battery, 
and that it furnishes a more uniform and less noisy cur¬ 
rent, which is an important consideration in vacuum tube 
work. These batteries run about 22 or 24 volts per unit, 
and two units can be used for amplifier operation. They 
can be readily recharged, since their ampere hour capacity 
is 2 or less. 


158 


RADfO FOR EVERYBODY 


All receiving sets and amplifier units are provided with 
jacks or binding posts for one pair of telephone receivers. 
If the jack is used—the jack is simply a metal hole or 
socket in which fits a plug fastened on to the cords of a 
telephone receiver—only one telephone receiver or head 
set can be used at a time. However, there has recently 
appeared on the market a multiple plug, which is inserted 
in the jack in the usual manner and which provides two 



Vibrating type of rectifier and stepdown transformer outfit 
for recharging storage batteries on the usual alternating cur¬ 
rent supply line. The vibrating reed, which appears under the 
handle, rectifies both sides of the alternating current so that 
direct current is obtained. The volume of direct current is 
indicated by the ammeter. 

holes or jacks for two head sets or for a head set and a 
loud-speaker, each instrument being provided with the 
proper plug. Furthermore, there is also available a mul¬ 
tiple jack which may be mounted on an instrument or on 
a table near the instrument. The multiple jack presents 
three jacks all connected in series and so constructed that 
one, two or three plugs can be inserted. As each plug 











RADIO FOR EVERYBODY 


159 


is inserted, it connects itself automatically in series with 
the circuit, while the unused jacks are short-circuited so 
that the circuit will remain closed except for the jack or 
jacks being used. The use of these devices is to be recom¬ 
mended where more than one person is to listen in. Of 
course, where binding posts are used for the telephone 
connection, two pairs of telephone receivers can be clamped 
under the binding posts. 

When the telephone receivers are connected directly 
with a vacuum tube detector, they may be arranged in 
parallel, but when they are used with a one or two-step 
amplifier, they should be arranged in series because of the • 
high voltage used. In the latter case they are arranged 
with one tip of each telephone set going to one of the 
binding posts, while the two remaining tips of the tele¬ 
phone sets are connected together, thus putting the sets 
in series. The use of the multiple jack or multiple plug 
simplifies this matter and makes positive and noiseless 
connections. 

A Few Pointers on Operating the Receiving Set 

With the fifty-seven varieties or more of receiving sets 
now on the market, it would be impossible to give precise 
directions on the operation of each set. However, the 
vacuum tube receiving sets fall into a few general classes, 
so that broad instructions on each class are certain to fit 
every individual case with due allowance made for the 
peculiarities of each particular set. 

The simplest vacuum tube set is of the single circuit 
type, in which no loose-coupler or vario-coupler is used. 
Furthermore, no regenerative action is employed, which 
greatly simplifies the operation but also makes the set 
less sensitive than it might be. Such a set makes use of 
a tuning coil or variometer, and perhaps a condenser. The 
inductance may be fixed, in the form of a compact in¬ 
ductance unit, with a condenser in series or in parallel 
to vary the wave length. However that may be, the ad¬ 
justment of wave length comes down to the one or two 
components, and is soon restored in each case. 


160 


RADIO FOR EVERYBODY 


The operation of the vacuum tube requires a little care. 
The filament rheostat must be varied until the best signals 
are obtained, after tuning them in to the utmost strength. 
Generally the signals are loudest and clearest when the 
filament rheostat is moved up to a point just before the 
hissing sound is heard in the telephone receivers. With 
most vacuum tubes, the plate voltage is critical for best 
results, so that the B battery should be varied in order 
to obtain the loudest and clearest signals. Either a B 
battery of the variable voltage type can be employed, or a 
rheostat can be placed in series with the battery and the 
» plate circuit. For the very best results, a potentiometer 
should be used with the B battery for the most accurate 
adjustments. The potentiometer is a resistance placed 
across the source of energy, while hooking up to one side 
and using a sliding contact to take current off the resist¬ 
ance at any point, thus making for very delicate control 
as compared with the simple series resistance of the usual 
rheostat. 

The use of the regenerative arrangement complicates 
the operation of a set not a little but it also makes for 
louder signals than could ever be obtained with a simple 
circuit. Regeneration is obtained either by means of a 
tickler coil or by a grid variometer, as a general thing. 
Take the case of the tickler coil, which controls the 
amount of regenerative or feed-back action. First the 
detector tube is adjusted until it is as near silent as pos¬ 
sible, yet responds to the spark signals.- This is generally 
before the point where the tube becomes noisy, although 
at times the temperamental tube works best when the 
rheostat has been moved past the noisy point and into 
another zone of relative silence. Then the tuning handle 
or handles are adjusted so as to bring in the desired sig¬ 
nals or telephone messages. Furthermore, by means of 
the tickler handle, the quality of the reception can be 
improved if necessary. If too much tickler action is used, 
the signals or the radio-phone are apt to be mushy and 
distorted because of excessive regeneration. Finally the 


RADIO FOR EVERYBODY 


161 


signals or radio-phone are refined by turning the vernier 
adjustment, if the set is provided with such a device. 
The vernier is simply an auxiliary tuner which deals with 
much finer variations than the main tuner. It is neces¬ 
sary in the best types of receivers, because regenerative 
circuits are extremely sensitive and sharply tuned for the 
best results. 

Generally, when using the regenerative method of recep¬ 
tion, a radio-phone station denotes its presence by a 
whistling sound as the tuner is varied. By moving the 
tuner back and forth over the entire range of wave 
lengths, whistling sounds may be detected at certain points. 
Then the tuner is finally adjusted so as to get in between 
these whistling sounds, where there is a silent zone. It 
is in this zone that the radio-phone music or talk is heard. 
At other times these whistling sounds are due to contin¬ 
uous wave or undamped wave transmitters, which, like 
the radio-phone, make use of the same kind of waves and 
therefore have the same characteristics. 

Once adjusted, a regenerative receiving set will main¬ 
tain its adjustment fairly well. Occasionally, the vernier 
or the tuner may have to be readjusted, especially if the 
character of the music, if one is listening in to a radio¬ 
phone concert, is changed materially. The filament 
rheostat may also be altered at times to improve the 
strength or the clarity of the music. 

When it comes to two- and three-circuit receiving sets, 
the tuning requires more care, otherwise the operation is 
the same. Again the tickler adjustment, starting at zero, 
is gradually increased until a position is reached just 
below the oscillating point. The oscillating condition is 
indicated by a soft hissing sound in the telephone. The 
final adjustments are maae with the vernier or verniers. 
Sometimes it may be found necessary to adjust the tuner 
and the tickler at the same time in order to maintain the 
proportion necessary to keep the receiver on the verge 
of the oscillating condition, which is the most sensitive 
one. The adjustment of the coupler will also be found 
most important, more so when one is endeavoring to cut 


162 


RADIO FOR EVERYBODY 


down interference to a minimum. After all, the main 
advantage of the two- and three-circuit receivers, over the 
single circuit regenerative receivers, is that they provide 
real means of eliminating troublesome interference. 


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How CW waves are detected with an undamped receiving 
arrangement. The CW wave is shown to represent the in¬ 
coming signals. The local circuit, employing a vacuum 
tube, is made to oscillate, producing its own wave or local 
current, which differs but slightly from the frequency of 
the incoming signals. This slight difference sets up a 
“beat current.” This beat current, in turn, modulates the 
plate current as shown, which is pulsating direct current, 
having been rectified from the alternating beat current. 
Finally the telephones slur the modulated plate current 
variations into the large pulsations indicated. 

Spark Signals and C W Signals 

The reception and amplification of spark signals will 
be most satisfactory when the regenerative action is con¬ 
trolled to a degree which will produce maximum ampli¬ 
fication without causing an oscillating condition in the 








RADIO FOR EVERYBODY 


163 


circuits. When the oscillating condition is reached, which 
is indicated by hissing noise, the tone of the spark signal 
will be destroyed and reception through interference will 
become virtually impossible. The tone of a spark trans¬ 
mitter, which means a damped wave transmitter, may be 
altered when adjusting the receiver from the plain de¬ 
tector action to the oscillating condition. That accounts 
for the fact why a transmitter, which is heard as a series 
of flute-like dots and dashes one moment, becomes a mushy 
but extremely loud series of dots and dashes the next. 
The flute-like sounds are the real sound values of the 
sparks, while the mushy sounds are the false sound values 
given to them by the oscillating action of the detector. 

What are known as continuous wave signals, including 
the interrupted continuous waves and the modulated con¬ 
tinuous waves, all of which are explained in the chapter 
further on dealing with continuous wave transmission, as 
well as the radio-phone, may be received in like manner, 
but a special condition may be obtained by allowing oscil¬ 
lations to take place in the receiver, producing the exact 
frequency of the incoming wave length. This is known as 
the “zero beat" method and in this condition amplification 
is greatly increased due to the augmented feed-back of 
energy from the plate to the grid circuit. It is only pos¬ 
sible to make use of this method while the incoming fre¬ 
quency remains constant, and its successful application 
requires considerable skill. 

In the reception of continuous waves the plate circuit 
feed-back or tickler action is to be increased to a point 
where oscillations are constantly taking place and this 
condition must be maintained throughout the entire tuning 
operations. 

The most successful means for reducing spark inter¬ 
ference while receiving modulated continuous wave sig¬ 
nals, including radio-phone, is the use of the zero beat 
method described above. This will cause the spark signal 
to become distorted and suppressed while greatly increas¬ 
ing the amplification of the desired signal. As the oscil¬ 
lating condition is a prerequisite in the reception of 


164 


RADIO FOR EVERYBODY 


continuous wave signals, it follows that spark signals are 
more readily suppressed than are the modulated contin¬ 
uous wave signals. Where the carrier wave length of the 
modulated continuous wave signal and the wave length 
of the undesired signal are almost identical, it may be ' 
possible to suppress the undesired signal by changing the 
frequency of the desired signal to the point where the 
carrier wave frequency of the modulated continuous wave 
signal is beyond audibility. The coupler adjustment also 
makes for additional freedom from spark interference. 
The elimination of continuous wave signals while receiving 
spark signals is easily accomplished by reducing the plate 
variometer or tickler dial settings until the oscillations 
cease, unless the continuous wave station is very powerful 
and located nearby. 

From Radio-Phone to Dots and Dashes 

Sooner or later, and better sooner than later, the radio 
enthusiast turns to dots and dashes because, after all. the 
radio telegraph still dominates the air as far as the volume 
of traffic is concerned. While the music and the radio¬ 
phone talks may be most interesting to the laity, the fact 
remains that many things of great importance are being 
missed if one does not understand the telegraph code. 

Formerly, the Morse telegraph code was largely em¬ 
ployed in radio telegraph work in this country. At that 
time the Marconi land stations and ship installations used 
the Continental code, which is the present code, while the 
other radio organizations as well as the Government and 
amateur stations used the Morse code, which is the code 
used on our telegraph lines. However, in order to have 
a uniform code with the rest of the world, the Continental 
code was finally adopted as the standard radio code. This 
code differs from the former Morse code in the fact that 
it has no spaces between the letters themselves. In the 
Morse code, for instance, the letter C is represented by 
dot dot space dot. The letter R is just the reverse, namely, 
dot space dot dot. Now, since there are spaces between 
the letters themselves, it stands to reason that the space 


Form 773 Bn 

Department of Commerce 

BUREAU OF NAVIGATION 

RADIO SERVICE 

INTERNATIONAL MORSE CODE AND CONVENTIONAL SIGNALS 

TO BE USED FOR ALL GENERAL PUBLIC SERVICE RADIO COMMUNICATION 

1. A dash Is equal to three dots. 

2. The space between parts ol the same letter is equal to one dot. 

3. The space between two letters is equal to three dots. 

4. The space between two words is equal to five dots. 

A . _ 

II — • • • 

Per'od.:. 

C _ . _ . 

Semicolon. 

I> -- 

E . 

Comma. ... 

F-- 

0 -- 

Colon. . . . 

II ... . 

I . . 

Interrogation. .. 

Exclamation point. . . 

h — . — 

L -- . 

Apostrophe. . 

M_ 

N — . 

Hyphen. .... 

P- 

Bar indicating fraction.... . . , 

Q - 

Parenthesis. . . 

R • — • 

s . . . 

Inverted commas. 

T _ 

U . . _ 

Underline. 

V . __ 

w _ 

Double dash. ... 

X - 


\ — • — — 

Attention call to precede every trans- 

Z — — • • 

mission. . • . 

A (German) ___ — 

General inquiry call. . . . 

1 or A (Spanish-Scandinavian) 

• - —- ■ • —— 

From (de) . . . 

CH (German-Spanish) 

Invitation to transmit (go ahead). . 

£ (French) . . — . . 

Warning — high power ... —, — 

S (Spanish)-.- 

O (German) ___ 

Question (please repeat after.) — 

Interrupting long messages. . .. 

II (German) . .- 

ait. . .... • - • • • 

Break (Bk.) (double dash) . 

Understand .— . 

3 • • • ■ 

Error . .. • • • * • • • • 

4 • • • • ■ ■ 

^ • • • • • 

. Received (0. K.) .— . 

6 .... 

7 — — * * • 

Position report (to precede all position 

messages) . . — . 

8 -- . 

End of each message (cross) .. — . — . 

9 -— • 

Transmission finished (end of work) 

11 — 6S60 

(conclusion of correspondence). . . 


Chart of the Continental radio code as now employed in alt raoio 

communication. 









































166 


RADIO FOR EVERYBODY 


between the dots and dashes forming a single letter must 
be shorter than those between letters, and it is this fea¬ 
ture which makes the code more complicated and more 
liable to error than the Continental code, which has no 
spaces within the letters themselves. 

The Continental code may be readily mastered with a 
little patience. The best method to proceed in learning the 
telegraph language is to learn the code letters not so 
much by remembering the dot and dash combinations 
as by learning the sounds. In other words, when an 
operator listens to a telegraph message he does not notice 
the dot and dash combinations of each letter and then 
translate these combinations into the proper letter or 
numeral. Instead, he catches the certain sound or com¬ 
bination of each letter or numeral, and automatically his 
trained mind reads off the message in letters. The 
trained operator never thinks of the letters in dots and 
dashes, just as the reader, in reading this line of type, 
does not notice the letters in each word but recognizes 
words as complete units by their general appearance. 
In writing, the same is true. The rapid writer does 
not think of each letter as he writes; his words are his 
units, and he writes as he thinks. 

Therefore, the code must be learned by means of some 
instrument which simulates radio dots and dashes. For 
this purpose a simple buzzer operated by a battery and 
a telegraph key, may be used. Again, one can purchase a 
regular practice set, which has buzzer and key com¬ 
bined in one unit. A very ingenious little practice set is 
shown in the accompanying illustration, which contains 
a battery, buzzer, telegraph key, and a lamp for visual 
signals. 

The first step, once the practice set is at hand, is to 
learn the code letter by letter. The code is given in the 
chart on page 165. Note that A is a dot and a dash 
This is translated into a short snappy push on the tele¬ 
graph key followed by a longer push. The key should be 
held with the index and middle fingers of the right hand 
resting lightly but firmly on top of the knob, with the 


RADIO FOR EVERYBODY 


167 


thumb in light contact at the side or beneath the rim of the 
key knob. All characters should be made by wrist motion, 
with the elbow stationary, and all muscles of the arm 
and fingers should remain perfectly flexible. One of the 
most difficult things for the beginner to learn is proper 
wrist motion, which is so essential to good' transmitting. 
The beginner should never start with the key knob close to 
the table, due to the fact that this will interfere with 
the forearm and free wrist movement. Transmitting in¬ 
volves a downward pressure on the key of short or long 
duration, it being unnecessary to do any elevating of the 

key as this is pro¬ 
vided for by the 
spring compression 
under the key. 

The beginner 
should first learn to 
recognize the letters 
of the 'Continental or 
International code in¬ 
stantly when heard, 
without conscious ef¬ 
fort. In order to ac¬ 
quire this knowledge 
he should start to 
send at a slow rate of 
speed, remembering that a ‘dash is equivalent in duration 
of time to that taken for making three dots. When opera¬ 
ting the key, listen to the sound produced by the buzzer, or, 
if the practice set has a visual indicator such as a lamp, 
watch the flash produced by the blinker, as it is called. In 
a surprisingly short time smoothness and speed in both 
sending and receiving will be developed. In some prac¬ 
tice sets a head receiver is worn so that the buzzes are 
heard in the same manner as though they were received 
from a radio telegraph transmitter. 

Taking the telegraph code, the beginner should start 
with the first four letters, mastering them in turn. Thus, 



Buzzer practice set employed in 
learning the radio code. This little 
set is also provided with a small 
lamp which grives visual code sigmals 
when desired. 



168 RADIO FOR EVERYBODY 

the beginner will note by studying the code chart that 
dah de dah de—and not dash dot dash dot—is C, in¬ 
stantly, and that dah de de de is B. In other words, he 
learns what sounds represent each letter, and he does not 
stop to figure how many dots and dashes he has heard. 
It is left to the mind to perform two functions for each 
letter, namely, to think of the symbol and then the letter. 
It will be found that as the code is mastered, the letters 
will form in the brain automatically, and when this stage 
is reached the speed can be greatly increased. 

After mastering the first four letters, the beginner goes 
on to the next four. With these mastered, he repeats 
all the letters from the beginning again, and then passes 
on to the next four, and so on. It may require several 
evenings to memorize all the letters and numerals, and 
finally one can go on to the various punctuation marks 
and other characters. To recognize the symbols instantly, 
even when they are sent at slow speed, takes much 
longer, of course. Sending is much simpler than receiving. 

With all the symbols memorized, the beginner should 
sit down by the hour and translate newspaper articles or 
magazine articles or any other “copy” into the Continental 
code, using the practice set. In this manner he trains his 
ear to the various sounds, and after all the mastering of 
the code is just that, nothing more. 

The next step is one which presents two alternatives: 
Either the beginner can get in touch with some other be¬ 
ginner and spend some time each week transmitting mes¬ 
sages back and forth to each other by means of a buzzer 
practice ,set, or the beginner can listen in on his receiving 
set to the amateur transmitting stations, endeavoring to 
pick up letters here and there. The second method is not 
apt to produce immediate results, for the reason that 
much of the traffic is entirely too fast for the beginner. 
However, certain radio telegraph broadcasting stations 
have the beginner very much in mind these days, and 
transmit at a very slow speed in order to furnish prac¬ 
tice for the beginner. There are automatic machines 


A group of young men learning the radio code. A telegraph key, high-pitch buzzer, and a couple of dry cells serve 
to simulate radio signals in the telephone receivers worn by the students and the instructor. The instructor sends 
out the messages, which are copied down by the students. At first the messages are simple and are sent at a slow 
rate of speed, but by degrees the speed is increased and the messages become more involved 








170 


RADIO FOR EVERYBODY 


which send messages at any desired speed for training the 
beginner. This is an excellent self-instructor. 

One method of learning the code is to attend a radio 
school. The schools, thanks to their wide experience, have 
perfected methods of training beginners which produce 
early results. But in the main one can teach one’s self 
if sufficient patience is exhibited. Listening to radio 
telegraph stations and attempting to jot down on paper 
as many letters as are recognized finally results in copy¬ 
ing more and more letters and words until perfection is 
attained. 

Aside from the telegraph code, there are certain abbre¬ 
viations that have been inaugurated by the International 
Radio Convention. The list of these abbrevations is pre¬ 
sented on the facing page, and while it may not neces¬ 
sarily be memorizd, it is well to remember the more im¬ 
portant ones. 

When and Where A Radio License is Necessary 

Having mastered the code and become a radio operator 
of more or less ability, a person can consider a trans¬ 
mitting set. Otherwise a transmitting set is out of the 
question, unless one has a licensed operator to run it. 
The owner of an amateur transmitting station must ob¬ 
tain a station license before it can be operated if the 
signals radiated therefrom can be heard in another state, 
and also if such a station is of sufficient power to cause 
interference with neighboring licensed stations in the 
receipt of signals from transmitting stations outside the 
state, which means that virtually all transmitters must be 
licensed. These regulations cover the operation of radio 
telephone stations as well as radio telegraph stations. 

Station licenses can be issued only to citizens of the 
United States, its territories and dependencies. 

Transmitting stations must be operated under the super¬ 
vision of a person holding an operator’s license, and the 
party in whose name the station is licensed is responsible 
for its activities. 


Form 772 a. 

Department of Commerce 

BUREAU OF NAVIGATION 

RADIO SERVICE 


INTERNATIONAL RADIOTELEGRAPHIC CONVENTION 

LIST OF ABBREVIATIONS TO BE USED IN RADIO COMMUNICATION 


ABBREVI¬ 

ATION 


QUESTION 


ANSWER OR NOTICB 


PUB 

3 RA. 

KB 

QUO 

TKD 


<JIU 

QUK 

QRL 


Do you wish to communicate by means of the 
International Signal Code! 

What ship or coast station Is that?. 

What Is yonr distance!. 

What Is yonr true bearing!. 

Where are yon bound for!. 

Where are yon bonnd fromt. 

What line do you belong to!. 

What Is yonr wave length in meters!... 

How many words have yon to send!. 

How do yon receive me!. 

Are yon receiving badly! ShaU I send 20!.. 


I wish to communicate by means of the 
International Signal Code. 

This Is. 

My distance Is.. 

My true bearing Is.degrees. 

I am bonnd for. 

I am bonnd from........ 

I belong to the.Line. 

My wave length is.meters. 

I have.words to send. 

I am receiving well. 

lam receiving badly. Please send 20. 


QSP 

% 
QST 
QSU 

*QSV 

QSW 

3 SX 
SY 

QSZ 

QTA 

QTE 

QTF 


foradjnstmentt. 

Are yon being Interfered with!. 

Are the atmospherics strong!. 

Shall I increase power!. 

Shalt I decrease power!. 

Shall I send faster!. 

Shall I send slower!. 

Shall I stop sending!... 

Have yon anything for me!. 

Are yon ready!. 

Are yon busy!... 

Shall I stand by?. 

When will be my turn!. 

Are my signals weak!... 

Are my signals strong!. 

Is my tone bad!. 

,Is my spark bad!. 

Is my sparing bad!. 

What is yonr time!. 

Is transmission to be in alternate order or in 
seriesl 


What rate shall I collect for. 

Is the last radiogram canceled . .. 

Did you get my receipt!... 

What Is your true course!. 

Are yon In communication with land!. 

Are yon in communication with any ship or 

'station (or: with.)1 

Shall I Inform.that yon are calling 

him! 

Is.calling met. 

WIU yon forward the radiogram!. 

Have yon received the general calit. 

Please call me when yon have finished (or: 

at.o’clock)! 

Is public correspondence being handled!.... 

Shall I Increase my spark frequencyT. 

Shall I decrease my spark frequency!. 

Shall I send on a wave length of. 

meters! 


• . . t . e . • .... 

What Is my true bearing! 
What is my position! .... 


for adjustment. 

I am being interfered with. 

Atmospherics are very strong. 

Increase power. 

Decrease power. 

Send faster. 

Send slower. 

Stop sending. 

I have nothing for yon. 

I am ready. All right now. 

I am busy (or: I am busy with.). 

Please do not interfere. 

Stand by. 1 will call yon when required. 

Yonr turn will be No. 

Yonr signals are weak. 

Yonr signals are strong. 

The tone is bad. 

The spark Is bad. 

Yonr spacing is bad. 

My time is. 

- Transmission will be In alternate order. 

Transmission will be In series of 5 message*. 
Transmission will be In series of 10 message*. 

Collect. 

The last radiogram la canceled. 

Please acknowledge. 

My true coarse is.degrees. 

I am not In communication with land. 

I am In communication with.. 

(through.). 

Inform...that I am calling him. 

Yon are being called by. 

I will forward the radiogram. 

General call to all stations. 

Will call when I have finished. 

Public correspondence Is being handled. 

Please do not Interfere. 

Increase yonr spark frequency. 

Decrease yonr spark frequency. 

Let ns change to the wave length of.... 

meters. 

Send each word twice. I have difficulty In 
receiving yon. 

Repeat the last radiogram. 

Yonr true bearing is.degrees from. 

Yonr position Is_latitude .... longitude. 


* Public correspondence is any radio work, official or private, handled on com¬ 
mercial wave lengths. 

When an abbreviation is followed by a mark of interrogation, it refers to the ques¬ 
tion indicated for that abbreviation. n—esso 


List of abbreviations now employed in radio communication for the 
purpose of saving time and trouble. 




















































































172 


RADIO FOR EVERYBODY 


The Government licenses granted for amateur stations 
are divided into three classes as follows: 

Special Amateur Stations, known as the “Z” class of 
stations, are usually permitted to transmit on wave lengths 
up to approximately 375 meters. 

General Amateur Stations, which are permitted to use 
a power input of 1 kilowatt and which cannot use a 
wave length in excess of 200 meters. 

Experimental Stations, known as the “X” class, and 
school and university radio stations, known as the “Y” 
class, are usually allowed greater power and also allowed 
the use of longer wave lengths at the discretion of the 
Department of Commerce, which has charge of the grant¬ 
ing of licenses and the enforcement of the radio laws. 

All stations are required to use the minimum amount 
of power necessary to carry on successful communication. 
This means that while an amateur station is permitted to 
use, when circumstances require, an input of 1 kilowatt, 
this input should be reduced or other means provided for 
lowering the antenna energy when communicating with 
nearby stations in which case full power is not required. 

Malicious or wilful interference on the part of any radio 
station or the transmission of any false or fraudulent dis¬ 
tress signal or call is prohibited. Severe penalties are 
provided for violation of these provisions. 

Special amateur stations may be licensed at the dis¬ 
cretion of the Secretary of Commerce to use a longer 
wave length and higher power than general amateur sta¬ 
tions. Applicants for special amateur station licenses 
must have had two years’ experience in actual radio com¬ 
munication. A special license will then be granted by 
the Secretary of Commerce only if some substantial 
benefit to the science of radio communication or to com¬ 
merce seems probable. Special amateur stations located 
on or near the sea coast must be operated by a person 
holding a commercial license. Amateur station licenses 
are issued to clubs if they are incorporated, or if any 
member holding an amateur operator’s license will accept 
the responsibility for the operation of the apparatus. 





















174 


RADIO FOR EVERYBODY 


Applications for operator’s and station licenses of all 
classes should be addressed to the Radio Inspector of the 
district in which the applicant or station is located, or, 
if this is not known, to the Bureau of Navigation, Depart¬ 
ment of Commerce, Washington, D. C. The accompany¬ 
ing map indicates the territory covered by each radio 
district. 

Each district has a Radio Inspector, whose address is 
given below: 

First District.Boston, Mass. 

Second District.New York City 

Third District.Baltimore, Md. 

Fourth District.Norfolk, Va. 

Fifth District.New Orleans, La. 

Sixth District.San Francisco, Calif. 

Seventh District .Seattle, Wash. 

Eighth District.Detroit, Mich. 

Ninth District .Chicago, Ill. 

Once more, let it be clearly understood that no license 
is required for a receiving set only or for the operator 
of a receiving set. However, all persons are required 
by law to maintain secrecy in regard to any messages 
which may be overheard. This is a blanket law, of course, 
intended to safeguard the interests of those transmitting 
and receiving 'private dispatches and special press reports, 
and does not apply to broadcasted telegraph and telephone 
service. 

Persons who wish to operate a transmitting set must 
apply to the radio inspector of their district for the neces¬ 
sary form and, at an appointed time, undergo an exam¬ 
ination which covers their proficiency in receiving and 
sending telegraph messages, as well as in the theory and 
practice of radio. Operator’s licenses are of the amateur 
and commercial grade, depending on the proficiencv of the 
person examined. There is no fee or charge for either 
an operator’s or a station license. 

Every person engaged in any form of radio communi¬ 
cation should have a copy of a pamphlet, “Radio Com¬ 
munication Laws of the United States,” which can be 












RADIO INSPECTION DISTRICTS 


















176 


RADIO FOR EVERYBODY 


secured by sending fifteen cents (not in stamps) to the 
Superintendent of Documents, Government Printing 
Office, Washington, D. C. 

The laws regulating the operation of private radio 
stations in Canada are different in several respects from 
those in force in the United States. For instance, a 
station which is used only for receiving must have a 
station license. For authoritative information, inquiry 
should be made of the Deputy Minister of the Naval 
Service, Ottawa, Ontario. 

Call Letters and What They Mean 

All radio transmitters have call letters. Just as auto¬ 
mobiles carry license plates with the State and a number 
plainly marked on them, so do all radio transmitting sta¬ 
tions use call letters consisting of two or three or four 
letters and numerals. If one station wishes to call an¬ 
other station, it calls by means of the call letters of 
the desired station. The Government assigns call letters 
at the time the station license is granted. Every radio 
amateur should have a copy of the pamphlets “Amateur 
Radio Stations of the United States,” and “Commercial 
and Government Radio Stations of the United States.” 
The price of each of the pamphlets is fifteen cents, and 
orders should be sent to the Superintendent of Docu¬ 
ments. These pamphlets contain lists of the amateur, and 
commercial and Government stations in the United States, 
and of the call letters assigned to the stations. A new 
edition of each pamphlet is published on June 30 of each 
year. A monthly publication called the “Radio Service 
Bulletin” is issued which contains information regarding 
changes in the radio regulations and traffic. 


Chapter VI. 


MAKING BIG SOUNDS OUT OF LITTLE 
ONES, OR THE GENTLE ART 
OF AMPLIFYING 


M UCH of the present success of radio depends on the 
amplifier apparatus now in use. The amplifier is 
the instrument which makes possible the magnifying of 
weak signals or sounds in an electrical circuit. An incom¬ 
ing radio-phone wave may be so weak that the sounds 
cannot be heard in the telephone receiver, yet throw in 
one step or stage of amplification and immediately the 
sounds are loud and clear. The music or the talk as¬ 
sumes a depth and roundness that has been lacking when 
receiving with the ordinary detector circuit. Throw in 
another step of amplification or two steps in all, and the 
sounds are so loud that they can be heard when the 
telephone receivers are laid on the table. Or, a loud¬ 
speaking device may be hooked up and immediately the 
sounds are heard throughout the room without the aid of 
the telephone receivers. 

The amplifier has served to increase the range of all 
transmitters to an unbelievable extent. Thus with a 
given transmitter in the old days of crystal detectors, the 
usual range might have been say 100 miles. Today, thanks 
to the regenerative receiving circuit already described, 
which amplifies the signals considerably, and also thanks 
to a two-step amplifier, the same transmitter may operate 
a thousand miles with ease. Not that the transmitter is 
any the more powerful or more efficient than it was 


178 


RADIO FOR EVERYBODY 


formerly, but the receiving set, because of the regenerative 
arrangement and the amplifier, responds when the waves 
are that much more attenuated or weakened. 

From Transatlantic Radio to Transcontinental 

Telephone 

The amplifier is responsible for many of our recent 
achievements. For instance, the recent spanning of the 
Atlantic 'by scores of amateur transmitters, using one 
kilowatt or less and a wave length below 200 meters, 
would have been impossible were it not for the highly 
efficient receiving sets and amplifiers employed by the 
British, French and other amateurs for the purpose of 
picking up the weak signals. An ordinary set would not 
respond to such signals, and the transmitters would be 
said, under such circumstances, to be incapable of spanning 
the 3,000 miles or more of space between America and 
Europe. 

Yet with the proper receiving set and super-amplifier, 
the transmitters were found to span the intervening space 
with a varying degree of success. Which only serves to 
prove once more that no matter how weak the trans¬ 
mitter may be, its waves are propagated through space 
and keep on going farther and farther away with virtually 
no end. It may seem fantastic to believe that the waves 
from a little amateur transmitter when once started keep 
on going through space for quite a while, until they may 
reach the moon and the distant planets; but such must be 
the case. The whole problem is one of having a receiving 
set sufficiently sensitive to respond to the attenuated waves, 
and then an amplifier which can build up the signals to 
audibility. 

The amplifier principle is used in telephone work. The 
trans-continental telephone would not be the success 
which it is were it not. for the vacuum tubes now em¬ 
ployed as amplifiers or repeaters. After going through 
many hundred miles of wire and becoming attenuated as 
a result, the weakened telephonic currents are passed 
through vacuum tubes in order to impress their charac¬ 
teristics on other circuits, which in turn have fresh and 


RADIO FOR EVERYBODY 


179 


powerful currents ready for another jump' of several 
hundred miles. These currents, in due course, become at¬ 
tenuated in their turn, and again resort is had to vacuum 
tube devices. The vacuum tube has proved to be the 
most reliable form of telephonic relay or repeater ever 



DETECTOR- 
AMPLIFIER 
SWITCH 


TUNIN6 

PANEL 


detector and amplifier filament 


Combination tuner and detector-amplifier set made up of two 
units mounted one above the other as shown. This comprises 
an excellent receiving set, with detector and two-stage ampli¬ 
fier completely self-contained. 


developed, working with virtually no distortion when 
properly designed and handled. 

In the previous chapter we had something to say re¬ 
garding the action of the vacuum tube. We learned of 
the flow of electrons or ions from the hot filament, and 
how this flow of electrons or ions formed a one-way 
bridge for the B battery current connected with the tele- 




















Hi|i|i|i|i|i|i|i|i—'^ nnnnnn 

w 

CD 1- 



\jisaumJ 



General scheme of connections for all audio frequency amplifiers. In this case a vacuum tube detector and two stages 
of audio frequency amplification are shown. GL,—grid leak; D—vacuum tube detector; A—filament battery; Rl, 2 
aiu j 3 _filament rheostat; B—plate or “B” battery; Tl, 2 and 3—intervalve or amplifying transformers; Am—ampli¬ 

fier tubes; LS—loud speaker. In actual practice the filament and B batteries are used for all three tubes, but In this 

and other hookups separate batteries are shown to simplify the diagrams. 









































RADIO FOR EVERYBODY 


181 


phones. And the grid, as we learned, is the control for 
the traffic over this one-way bridge. In the case of the 
amplifier tube, the grid is again employed as the control 
Instead of using a pair of telephone receivers in the 
plate circuit of the receiving set, the two leads or “out¬ 
put” terminals are brought to the amplifier apparatus, as 
shown in the accompanying diagram. The first step is 
to pass the receiving circuit current through the primary 
of a special amplifying transformer. Such transformers 
are available in many different styles but all serve the 
same general purpose. They are sometimes called inter¬ 
valve transformers. The secondary of the transformer 
is brought to the grid and to the filament of the amplifier 
tube, as shown. The plate circuit of the amplifier tube 
contains a B battery of higher voltage than the detector 
B battery, and the telephone receivers. However, if an¬ 
other stage or step of amplification is desired, then the 
plate current from the first tube is brought to the primary 
of a second amplifying transformer, and the secondary 
is connected with the grid and filament as before. This 
second amplifier bulb has a B battery and a pair of tele¬ 
phone receivers or the loud-speaking device, as the case 
may be. A third step may be added in the same manner. 
Three steps or stages of amplification are considered the 
limit in actual practice, for the reason that beyond that 
point the adjustment of the circuits becomes too difficult 
for satisfactory work. Please note that the same fila¬ 
ment and B battery may be used for the detector and the 
amplifier tubes, but for* the sake of simplicity most of our 
diagrams show separate batteries being used for each 
tube. 

Whereas the amplifier tubes and detector tubes may 
look alike, they are quite different as far as the electrical 
characteristics are concerned. Amplifier tubes are not 
critical in adjustment when compared with detector tubes 
and they will operate successfully on plate voltages of 40 
to 80 volts. Where a detector and two stages of ampli¬ 
fication are used, three 22 1 / 2 volt units may be connected 


182 


RADIO FOR EVERYBODY 


ru. ament rheostats intervalve transformers tube sockets 



Simple mounting: for a two-stage amplifier, comprising the fila¬ 
ment rheostats, the intervalve or amplifying transformers, and 

the tube sockets. 

in series and connections to the receiver made in a manner 
which permits the use of the full voltage on the amplifier 
tubes while a variable portion of the same battery is 
used for the detector tube, say anywhere from 16 to 22 
volts. Where extremely loud signals are desired the 
plate voltage may be 100 or over; and while such high 
voltage will not damage the amplifier, it will increase 
tube noises, and is therefore not desirable when receiving 
signals with the telephone head set. No more than 45 
volts is required even with several pairs of head phones. 
An amplifier tube which requires a critical plate voltage 
or filament current adjustment will not give consistently 
satisfactory results as an amplifier. Tubes of this charac¬ 
ter will generally be found useful as detectors. 

Audio or Radio Frequency—Which? 

The amplifying arrangements described so far, and for 
that matter the greater part of the amplifying apparatus 







RADIO FOR EVERYBODY 


183 


now available and in regular use, is known as the audio¬ 
frequency type. It is called the audio frequency type 
for the reason that it is handling currents of frequencies 
well within the audible range. There is another type of 
amplifier known as the radio-frequency type, which, up 
till the present time, has been rarely used. However, at 
this writing the radio frequency type is rapidly coming 
into general use for long-range reception, as well as in 
connection with loop antennae and diminutive antennae of 
all kinds. In the case of audio-frequency amplification, the 
amplifying is done after the signals have been passed 
through the detector and rectified so as to produce audio¬ 
frequency currents, while with the radio frequency ampli- 



Components of a combination radio frequency amplifier, vacuum 
tube detector, and audio frequency amplifier, mounted in a neat 

steel cabinet. 









184 RADIO FOR EVERYBODY 

fier the waves are amplified before they are passed to 
the detector. 

The advantage of the radio-frequency amplifier lies in 
the fact that it amplifies only the wave and not the 
many little irregularities and imperfections which exist in 
the usual receiver and amplifier equipments. Further¬ 
more, most detectors have a critical point at which they 



SWITCH FOR DETECTOR OR 
AMPLIFIER CONNECTION 


Two-stage audio frequency amplifier, with filament rheostat 
handles, switch handle for connecting the detector alone, or 
one stage or two stages of amplification into the circuit, as 
well as the input, output, and filament current binding posts 
mounted on the front panel. 


begin operating. Signals which come in weaker than the 
critical point of the detector make no impression on the 
detector, and are therefore lost entirely. No matter how 
many steps of audio-frequency amplification may be piled 
up behind the detector, the signal which has failed to 














RADIO FOR EVERYBODY 


185 


actuate the detector will certainly not be heard. With 
radio-frequency amplification, on the other hand, there is 
virtually no critical point, and even the weakest signal is 
built up to the desired degree before it is passed on to 
the detector, there to be rectified to audio-frequency cur¬ 
rent, which, if desired, can be passed on through one or 
more stages of audio-frequency amplification in order to 
build up the signal strength. 

In extreme long-distance work, it is not uncommon to 


FC VC 



The wire marked 1 is the grid wire from the tuner. R are 
the filament rheostats; Rl, 2 are resistances; Am are ampli¬ 
fier tubes; D is the detector tube; FC—fixed condenser; T— 
telephones; VC—variable condenser. 

find two stages of radio-frequency amplification, followed 
by a detector and two stages of audio-frequency amplifi¬ 
cation. 

When using a loop antenna, it is usually necessary to 
employ radio-frequency amplification unless one is near 
the desired transmitter. The radio-frequency amplifier 
builds up the wave energy before passing it on to the 
detector, and in that manner enables one to hear signals 
which would not affect the detector otherwise. After 
all is said and done, it is really the radio-frequency ampli¬ 
fier which makes for extreme sensitiveness in the receiv- 





































186 


RADIO FOR EVERYBODY 


ing set, and enables almost unbelievable distances to be 
spanned, while it is the audio-frequency amplifier which 
makes for loud -signals and for the successful operation 
of loud-speaking devices. 

The simplest type of radio-frequency amplifier is 
known as the resistance-coupled type, and is shown in the 
wiring diagram on page 185. In this arrangement the 
amplifying transformers are replaced by suitable resis¬ 
tances and condensers, the amplified energy being passed 
from one circuit to the other by means of the resistance 
coupling. This method is preferable in many instances 
because of its simplicity and because of the fact that 
the radio or the audio frequency can be amplified at will. 

If the grid condenser is eliminated on some of the tubes 
in a multi-stage amplifier, as shown in the diagram on 
page 185, then the incoming radio frequency is amplified 
before it is rectified, and after it is rectified by going 
through the detector tube it is then amplified again at 
audio frequency in order to obtain volume of sound. 
Amplifying at radio frequencies, although it is rather diffi¬ 
cult to do so at times, has numerous advantages and the 
experimenter is urged to try amplifying at radio fre¬ 
quencies wherever possible since one of the principal 
advantages of this method is that radio frequencies are 
inaudible to the human ear and the amplifying action 
is therefore carried on without unpleasant noises to the 
listening operator. 

By using special transformers the transformer method 
can be applied to radio frequency amplification, reducing 
it to something almost as simple as the audio-frequency 
amplifier. There have been introduced of late special 
radio frequency transformers which function over the 
wave length band of 200 to 5,000 meters, and which have 
been designed particularly for the short wave band of 
200 to 500 meters. These transformers mark a real 
step forward in the art, and must make for the wide appli¬ 
cation of the radio frequency method of amplifying. This 
method of amplification doubles and triples the receiving 
ranges; it makes signals audible that cannot be received 


One-step radio-frequency amplifier and vacuum tube detector arranged with the regenerative hook-up. LC _loose- 

coupler or vario-coupler; VI—variometer In grid circuit; Ci—ground; R—filament rheostats; R1 and R2—additional 
rheostats; A—filament battery; Am—amplifier tube; GL— grid leak; D—detector; V2—variometer in plate circuit, for 

feed-back; VC—variable condenser; T—telephone; 15—plate battery. 



































188 


RADIO FOR EVERYBODY 


with other types of amplifying circuits; it is vastly 
superior to any other method of amplifying telephone 
speech; it eliminates tube noises; it increases selectivity ; it 
increases signal audibility at each stage at least 'twenty 
times; it makes possible the use of small loops or frame 
antenna to receive as well as with high antennas; and it 
gives a 20-watt amateur radio telephone set the trans¬ 
mitting range of a transmitter of several times the power. 

Please note that radio-frequency amplification can be 
used in connection with any existing receiving set, even 
if said set is of the simplest and most elementary type. 



amplifier tube; HI. 2, 3, 4—rheostats; PS—primary and sec¬ 
ondary of intervalve or amplifying transformer T; GL.—grid 
leak; D—detector; 11—plate battery; A 1 and 2—filament bat¬ 
tery; PC—fixed condenser; T—telephones; TICK—tickler 

coil; G—ground. 

For radio-frequency amplification builds up the wave 
strength before it is passed on to the detector, so that 
in every sense of the word it is as though the receiving 
set were moved a considerable distance towards the trans¬ 
mitter. Thus a crystal detector can be used in conjunction 
with the radio-frequency amplifier, for after the wave 
strength has been built up by the radio-frequency ampli¬ 
fier, it is rectified by the crystal detector. Then, if de¬ 
sired, the rectified current from the crystal detector can 
be amplified by means of audio-frequency amplifiers. 




































RADIO FOR EVERYBODY 


189 


Sometimes the crystal is employed in this manner, for 
the reason that it is silent in its operation and is not apt 
to introduce noises into the circuit. 

When and Where to Use an Amplifier 

Most receiving sets are complete without an amplifier. 
In other words, the amplifier is something apart from the 
regular receiving set; it is an accessory; it can be added 
at any time to the usual run of receiving sets. So the 
question arises as (to when and where an amplifier should 
be employed. 

The amplifier of the audio-frequency type, which is the 
type generally used, should be employed when loud sig> 
nals are required. Take the case of the radio-phone 
service, for instance. At a reasonable distance the music 
and talk come in good and clear, but it cannot be denied 
that the music and talk are generally thin, so to speak. 
The music or the talk has no depth, no sense of realism. 
It seems to be in one plane, just like the motion picture 
is in one plane when viewed on the ordinary screen. It 
lacks the depth so necessary for realism, even though it 
may be quite loud. At least those are the author’s obser¬ 
vations, as well as those of many persons who have 
listened in on his receiving set. However, the moment 
the amplifier is used, even with one step, there is introduced 
a loudness and clarity, as well as depth, which make for 
realism. These features are particularly noticeable in 
the case of a radio chapel service, where the minister may 
be preaching and is followed by the choir. Without 
amplifiers, the voice of the minister and the voices of the 
choir are on the same plane, but with the amplifier we 
obtain a sense of depth and the entire rendition sounds 
as though it were in a large church. 

So the amplifier, then, makes for better results, let alone 
loudness. Fortunately, an amplifier is not such an elab¬ 
orate piece of mechanism. It consists merely of a 
vacuum tube of the amplifier model, a filament rheostat, a 
transformer, and the necessary batteries and connections. 
Like the vacuum tube detector, it requires a filament 


190 


RADIO FOR EVERYBODY 


battery and a high-voltage B battery. When telephone 
head sets are to be used, only 45 volts is required for the 
B battery. In that case two B battery units of 22 l A 
_ volts each are connected 

in series, and a tap is 
taken from the connec¬ 
tion between the units 
and brought to the de¬ 
tector in order that the 
detector will not have 
more than 22A volts, 
while the amplifier will 
have the full voltage. 
It is well to mention 
here that a variable 
voltage battery should 












LOOP 











Li 


L 2 



A 

Bow the radio-frequency amplifier is used with the loop 
antenna for Ions: distance reception. VC 1—variable con¬ 
denser across loop terminals; L, 1 and L. 2—inductance coils; 
VC 2—variable condenser; FC —fixed condenser; Am—amplifier 
tube; I)—detector tube; T—telephone receivers; B—plate bat¬ 
tery; A—filament battery; R 1 and 2—filament rheostat. Note 

the extra resistance. 


i 












































RADIO FOR EVERYBODY 


391 


be used for the detector, since a good detector tube has a 
critical voltage adjustment for the B battery, and a fixed 
voltage battery for the other unit. Some battery manu¬ 
facturers are now supplying a combination B battery of 
45 volts, with part of the battery made variable so as to 
obtain the critical B battery voltage for the detector. 

Amplifier units can be purchased at a reasonable cost. 
They come in one-stage and two-stage models, and in 
some instances a three-stage model can be obtained, al¬ 
though this model is rare for the reason that its adjust¬ 
ment calls for considerable skill as compared with the one 
and itwo-stage models. Then again, there are units avail¬ 
able in which the detector is included. Thus one can 
obtain a detector and one-stage model, and a detector and 
two-stage amplifier model. 

Fortunately, the same storage battery is employed for 
ithe detector and the amplifier tubes, just as the B battery 
is used for all the tubes of one set. This simplifies the 
problem and makes for economy. 

A soft or gassy tube, known as a detector tube, should 
be used for the detector, while hard or highly exhausted 
tubes should be used for the amplifiers. However, in 
some sets where a single rheostat may be employed for 
the detector and amplifier tubes, and a rigid B battery 
voltage is used on all tubes, it is sometimes good practice 
to use amplifier tubes throughout, including detection. 
This is not the most efficient practice, but it makes for 
simplicity, since amplifier tubes do not require the delicate 
manipulation and adjustment that are called for with soft 
or gassy tubes. Of course, the sensitiveness when using 
amplifier 'tubes throughout is bound to be greatly reduced, 
for it is the delicate adjustment of the gassy tube which 
makes it so highly responsive to weak signals. 

The Question of Loud Speakers 

Sooner or later the radio enthusiast wants to do away 
with head ’phones in order that the radio-phone service 


192 RADIO FOR EVERYBODY 

may be used for danc¬ 
ing or even for enter¬ 
taining a roomful of 
persons. In that event 
some form of loud¬ 
speaker must be used. 

The simplest form 
of loud-speaker is one 
which makes use of 
the existing receivers, 
without extensive al¬ 
terations of the re¬ 
ceiving and amplify¬ 
ing arrangements. 
There are horns avail¬ 
able which may be 
fitted to the regular 
telephone head set. 
These horns are pro¬ 
vided with soft rub¬ 
ber pieces or even 
with clamps, so that the regular head set may be held in 
place while the sounds from both receivers travel up 
through a horn and are amplified so as to be audible some 
distance away. These devices are excellent in a limited 
way, and their main attraction is the fact that they can 
be used without alteration of any kind. 

However, where something of a more ambitious nature 
is wanted, it becomes necessary to use special loud- 
speakers. The simplest loud-speakers are those which 
.make use of a single telephone receiver of the same 
.general type as those used with head bands, as well as a 
special horn. There are all kinds of devices of this gen¬ 
eral class, ranging from horns of pressed paper or wood 
pulp, made in the general form of the channels of the 
human ear, and pressed copper reflectors, as well as horns 
of a more conventional design. 



Lroud-speaker attachment that fits on 
the tone-arm of any phonograph so 
that the usual horn of the phonograph 
is used to amplify the sounds. 



RADIO FOR EVERYBODY 


193 



One of the most popular forms consists of a specially 
designed metal horn mechanically attached to the mechan¬ 
ism of a special telephone receiver, in which the stand¬ 
ard mica diaphragm has been replaced by a strong corru¬ 
gated metal diaphragm which will stand practically any 
amount of abuse without damage. A large amount of 
experimental work was carried on by radio experts before 
final decision was made on the horn and it is believed 
that the design furnishes as fine a quality of reproduc¬ 
tion as can be obtained except through the use of a 
very elaborate sound chamber such as is found in high- 
priced phonographs. 

The loud-speaker in question, which is shown in the 
accompanying illustration, will work satisfactorily from 
a two-stage audio-frequency amplifier and, using good 
amplifying tubes, 150-200 volts 
may be used without damage 
to the instrument. By good 
tubes is meant, in this case, 
especially ‘‘hard’’ 
tubes. The usual am¬ 
plifying tubes are 
operated on 45 volts, 
and this voltage will 
produce only weak re¬ 
sults with the usual 
' loud-speaker. If more 
B battery is added, 
such as by connecting 
a third and even a 
fourth unit to the 
usual B battery, the 
results may be poorer 
with the regular am¬ 
plifier tubes. 

Some radio workers 


use the 5-watt trans¬ 
mitting tubes as am¬ 
plifiers, in which case 


One of the several loud-speakers now 
available for home use. This model 
may be used in connection with any 
two-stage amplifier. 







194 


RADIO FOR EVERYBODY 


voltages up to and even exceeding 100 volts may be ap¬ 
plied : In such an arrangement it is well to try the 5-watt 
tube in the second stage of amplification, and to use the 
regular amplifier tube in the first stage. 

One form of loud-speaker which is proving very popu¬ 
lar is a simple telephone receiver of special construction 
which may be attached to the tone arm of the usual phono¬ 
graph. In this manner one saves the cost of a special 
horn, and at the same time one has the pleasure of hear¬ 
ing the regular phonograph do duty as a radio receiver. 
The results with such an arrangement are very good, 
and the volume may be made extremely great by using 
sufficient voltage on the telephone. 

Loud-speakers require plenty of voltage, and there is 
no getting away from this fact. The simple devices which 
take the the regular head sets or single receiver operate 
off the regular amplifier output without changes of any 
kind; but when it comes to filling an entire room with 
loud music or talk, the problem becomes quite complicated 
and certainly expensive. 

Too many laymen are of the opinion that if the head 
’phones respond quite loudly to the nearby broadcasting 
station signals, then all they must do is to attach a loud¬ 
speaker and get sufficient sound volume to fill a large 
room. Or again, their plan may be to attach a horn to 
the head ’phones, and thus project the sounds throughout 
the room. Such is not the case, however, in cold practice. 
It must be remembered that there is a vast difference 
between setting into vibration the few cubic inches of 
air which are trapped between the cap of a receiver and 
the ear, and setting into vibration the many hundred cubic 
feet of air in the average room. It requires ever so much 
more power to set many hundred cubic feet of air into 
vibration. Another way to express the problem is in terms 
of relative electrical force and sound. Whereas a one- 
stage amplifier may increase the electrical energy 400 
times, and the second stage 400 times more, or 160,000 
times, the sound strength is augmented about six times 


RADIO FOR EVERYBODY 


195 


by the first stage, and perhaps no more than twenty times 
with the second stage. 

Limitations of the Ordinary Telephone Receiver 

The ordinary telephone receiver such as is used on our 
present-day telephone lines and for our usual head ’phones 
in radio, operates on the electromagnetic principle. The 



Special power amplifier, used in connection with extra power¬ 
ful loud-speakers such as are employed for projecting: the radio¬ 
phone entertainment in a large hall. This amplifier is used in 
addition to the usual amplifier of the receiving set. 


voice current passes through a winding on a permanent 
magnet, changing its magnetic intensity or flux and con¬ 
sequently varying its pull on a diaphragm placed directly 
over the pole ends. Its weakness lies in the fact that if 
the diaphragm is placed at a distance away from the pole 
pieces, the magnetic pull is greatly lessened; and on the 




196 


RADIO FOR EVERYBODY 


other hand, if the diaphragm is placed too close, it hits 
the poles. A compromise position is selected whereby the 
diaphragm is placed at such a distance from the poles 
as to allow some motion before hitting the poles, and yet 
near enough to get a fair magnetic pull. Another weak¬ 
ness is that the diaphragm is under tension always and 
has to be made stiff to withstand this tension. All types 
of receivers using the electromagnetic principle will give 
forth sound only up to a certain strength, and then the 
diaphragm will hit the poles, producing marked distor¬ 
tion. However, for use in head sets the usual electromag¬ 
netic type of receiver is quite satisfactory, since, as al¬ 
ready stated, only a small volume of air must be vibrated 
to produce ample volume of sound in the ears. 

Thus for the generation of large volumes of sound, it 
has been necessary to work out a different kind of tele¬ 
phone instrument. Instead of using electromagnets act¬ 
ing directly on a diaphragm, most loud-speakers make 
use of a movable coil which is placed in a powerful mag¬ 
netic field and which, through a system of levers and rods, 
transmits its fluctuations to a diaphragm. In this manner 
the diaphragm is in no way directly concerned with the 
magnetic flux. There are no pole pieces to interfere with 
free motion, which mav then be as great as the elastic limit 
of the diaphragm. A large horn attached immediately 
above the diaphragm provides the air column for the 
diaphragm to move. It will also be noted that the system 
of transmission between the armature, or member which 
is affected by the magnetic flux which in turn is affected 
by the fluctuating current, and the diaphragm, is such as 
to make for marked amplification of the mechanical order. 

Now a loud-speaker of the electro-dynamic kind requires 
considerable power to operate, and the usual current from 
the vacuum tube detector and even from a one or two- 
stage amplifier is quite insufficient, as a general rule. A 
power amolifier is required to operate the usual loud¬ 
speaker. This is an amplifier making use of larger vacuum 
tubes than the usual amplifier tubes. The Radiotron 


INPUT 


RADIO FOR EVERYBODY 


197 



Complete Western Electric type of loud-speaker and amplifying: 
unit, showing: the wiring: of same. 


OUTPUT 

































































198 


RADIO FOR EVERYBODY 


5-watt transmitting tube or the Western Electric 216A 
is employed in power amplification. Some types of powei 
amplifiers operate directly from the detector circuit. The 
Western Electric amplifier is of this category. It amp¬ 
lifies the detector output some one hundred thousand times 
before passing it on to the loud-speaker. The W estern 
Electric amplifier has two stages of amplification and 
makes use of three tubes. One tube is used for the first 
stage of amplification; the other two are connected on 
the so-called differential or push-and-pull principle, for 
the second stage. The differential connection of the tubes 
for the second stage insures faithful reproduction of 
sounds without overloading; also, by employing the partic¬ 
ular scheme of connections found in this amplifier, the 
circuit is compensated in a manner to secure the highest 
degree of faithfulness in tone and speech reproduction. 

The Fifty-Seven Varieties of Loud-Speakers 

At the time the first edition of this book was being 
written, there was practically no choice in the matter of 
loud-speakers. There was but a single reliable loud¬ 
speaker on the market. Since that time more and more 
loud-speakers have made their appearance, ranging in price 
from $20.00 to several hundred dollars. Many manu¬ 
facturers of loud-speakers claim for their devices that a 
power amplifier is unnecessary, and that they can be 
operated directly off the usual amplifier. The truth of 
the matter is that a true loud-speaker, as distinguished 
from an ordinary electromagnetic receiver provided with 
a horn, requires considerably more power then can be 
obtained from the usual amplifier. Even with the small¬ 
est true loud-speakers, at least a one-stage power ampli¬ 
fier is required. This one-stage amplifier may either be 
bought as a complete unit, or it may be assembled from 
standard parts, such as a 5-watt Radiotron or W. E. 216A, 
a socket, a heavy rheostat, an extra sized transformer, and 
the necessary connections, binding posts, B batterv and 
filament battery. 


RADIO FOR EVERYBODY 


199 



The public and commercial history of the electro¬ 
dynamic receiver is very interesting. Its initial bow to 
the public was made on Christmas Eve, 1915, at the 
Municipal Christmas Tree Celebration at San Francisco. 
That it fulfilled the expectations of the inventors, E. S. 
Pridham and P. L. Jensen of Oakland, Calif., may.be 
fully realized in the words of the San Francisco Bulletin 
of the following day: “The slender tone of a single violin 
plainly heard a mile away; Tetrazzini’s voice on a phono¬ 
graph record resounding from end to end of the vast 
stadium; the words of Thos. W. Hickey reading Lincoln’s 
Gettvsburgh address reverberating like the roar of a giant; 
a piano solo resemb¬ 
ling the chimes of 
Westminster Abbey 
played by a Colossus 
of Rhodes — these 
things made possible 
by the new inven¬ 
tion.” 

After this first 
demonstration, at¬ 
tended b y 50,000 
people, the electro¬ 
dynamic receiver has 
officiated at nearly 
every large gathering 
of public importance 
since the war, where 
speakers needed am¬ 
plification of their 
voices. During the 
war no demonstra¬ 
tions were made be¬ 
cause of the great 
pressure of Govern¬ 
ment orders in the 
factory producing 




.v."TW'"' 1 . T? 


Another type of loud-speaker, larger 
than the one shown on the facing page 
and intended for a medium-sized hall. 






200 


RADIO FOR EVERYBODY 


the loud-speaker in question. Several notable ex¬ 
amples of what has been done since that time with this 
loud-speaking apparatus are: Ex-President Wilson spoke 
at San Diego to 50,000; at Reno to 6,000 in three different 
theatres at the same time. The Prince of Wales spoke 
to 30.000 also at San Diego. The Victory Loan was 
opened by an aviator delivering a speech by radiophone 



The mechanism of the electrodyiiamic type of loud-speaker, 
consisting of the pole pieces of the electro-magnet, the movable 

coil, and the diaphragm. 


and loud-speaker to 30,000 at Washington, D. C. Presi¬ 
dent Harding and his political opponents used the electro¬ 
dynamic loud-speaker constantly during their campaigns 
to talk to crowds varying from 40,000 to 100,000 in the 
case of ex-Governor Cox at Sheepshead Bay. Many 
other instances may be cited where this apparatus has 
made it possible for a single speaker to address enormous 
crowds, notably the Armistice Day ceremonies at Arling- 





RADIO FOR EVERYBODY 


201 


ton, Va., on November 11th, 1921, when the American 
Unknown was put to rest. 

On the Armistice Day in question, President Harding’s 
address and the prayers and the songs at Arlington were 
heard as clearly and with as much feeling by 30,000 
persons in New York City and 20,000 in San Francisco 
as though each member of these audiences had been 
among the specially invited guests within the Arlington 
Amphitheatre. In addition to these, at least 100,000 
persons scattered on the hillsides outside the Amphitheatre 
also heard the entire ceremonies with little difficulty. The 
combined audience of 150,000 is by far the largest which 
ever heard a speaker at one time, and the fact that the 
assemblage was partly on the Eastern Coast and partly 
on the Western makes the event even more remarkable. 

Amplification That Runs Into the Billions 

The electrical amplification involved in the loud-speaker 
installations of the foregoing kind must be truly enormous, 
requiring such numbers to express it as those with which 
astronomers delight to startle the imagination. Calcula¬ 
tions show that the loud-speaker at Arlington was cap¬ 
able of stepping up the energy of the telephone current 
coming from its transmitter considerably over one billion 
fold. The extreme case of amplification, however, was 
that involved in reproducing the Arlington ceremony at 
San Francisco. The total amplification within the trans¬ 
continental line was over one hundred million million fold. 
Combining this amplification of the line with that imparted 
to the telephone current before reaching the line in Arling¬ 
ton and after leaving it at San Francisco, gives the total 
amplification as about ten trillion trillion fold, or 10,000,- 
000,000,000,000,000,000, if one prefers to see it written 
thus. And it should be borne in mind that this trillion 
trillion fold amplification was so accurately controlled and 
applied that the audience at San Francisco heard the 
speeches and songs as realistically as though they were 
standing but a few feet from the speaker’s stand at Ar¬ 
lington. 


202 


RADIO FOR EVERYBODY 


Odds and Ends of Amplification 

Amplification is not so simple as it seems at first glance. 
True, an amplifier consists of nothing more than a tube, 
socket, rheostat, transformer, and batteries; but what 
kind of tube, socket, riieostat, transformer, and batteries? 
In other words, this part of a radio set should never be 
slighted, despite its seeming simplicity and the fact that 
it is the last piece*of apparatus to be added to a set at a 
time when the available funds may be down quite low. 

At this particular moment in the history of popular 
radio there are many different kinds of radio supplies 
on the market. The buyer is only too often taken off 
his guard by price considerations. Thus the choice may 
fall on a low-priced socket, a cheap transformer, an in¬ 
expensive rheostat, and so on. But, remember, the cheap¬ 
est is often the most expensive, because it must soon be 
replaced by the more expensive but reliable apparatus, and 
the builder is therefore put to that much extra expense. 

It pays to use the best transformers. An inquiry here 
and there among amateurs and others who have done con¬ 
siderable radio work will soon disclose the best makes 
of transformers. It so happens that transformers are 
available in various ratios between the primary and secon¬ 
dary windings, such as 2y 2 to 1, 3 to 1, 4 to 1, and even as 
high as 9 to 1. It is advisable to use the lower ratios if 
two stages of amplification are to be employed regularly, 
and the operator does not mind the expense of an addi¬ 
tional tube. With transformers of 2*4 to 1 ratio it is 
possible to operate three amplifier tubes at one time with 
a minimum of distortion. In fact, one of the standard 
amplifiers on the market is a two-stage unit which is used 
in conjunction with a companion unit consisting of a de¬ 
tector and one stage, making three stages in all. Due to 
the 2 ]/ 2 to 1 ratio of the transformers, three stages are 
practicable in this case. 

If but a single stage of amplification is to be used, a 
higher ratio of amplification is permissible. The author 
has employed various makes of transformers, some as 


RADIO FOR EVERYBODY 


203 


high as 9 to 1 ratio, with good results. With the higher 
ratio transformers, especially with two or three stages 
and in connection with a loud speaker, it is a good plan to 
“bias” the grid. In the last chapter of this work there is 
a short section dealing with the biasing of the grid of an 
amplifier by means of a potentiometer, if not more than 
50 to 60 volts is employed for the “B” battery, and a “C” 
or grid battery if higher “B” battery voltages are em¬ 
ployed. 

When using head-phones in connection with an ampli¬ 
fier, it is well to bear in mind that they should be con¬ 
nected in series. There is considerable voltage available 
when using one or two stages of amplification, so that 
the telephones should be connected in series in order to 
give the best results. As many as six pairs of 3,000-ohm 
head-phones may be connected in series on a one-stage 
amplifier without reducing the volume of sound in each 
receiver materially. On the other hand, when using sev¬ 
eral head-phones on the plain detector circuit, it may be 
well to limit the number in series to two, or possibly 
three. 

While many instructions for building a receiving set 
point out that the “B” battery may be used in common 
by the detector and the amplifier, the fact remains that 
it is better practice to use separate batteries. The detector 
tube requires a 22 l / 2 -\o\t variable “B” battery, while the 
amplifier takes a plain 45-volt unit. The use of a common 
“B” battery is apt to make for an interplay of energy 
between circuits, with subsequent howls. 

Hard tubes should be used for amplifying purposes. 
While the hard tube may be employed as a detector with 
fair results, the usual detector tube, which is a soft or 
“gassy” tube, will not work well as an amplifier. The 
WD-11 dry cell tube is a hard tube and makes out well 
as an amplifier, except that it is somewhat microphonic or 
“noise reproducing.” The adjustment of the rheostat or 
the movements about the table on which the tubes are 
mounted, produce slight vibrations of the tube elements 
which in turn produce noises in the head-phones. It is 


204 


RADIO FOR EVERYBODY 


good practice to mount these tubes on spring supports or, 
simpler yet, mount the socket support on small pieces of 
spongy rubber. 

Whether the amplification is for the purpose of obtain¬ 
ing louder responses in the usual head set, for operating 
the loud-speaker in the living room, or for addressing 
tens of thousands of citizens, the principle remains the 
same. Vacuum tubes are employed to connect a weaker 
circuit with a more powerful circuit, so that the weaker 
energy may act as a trigger to release the energy of a more 
powerful circuit, and so it goes from the first stage to 
the second and the third and so on until the desired power 
has been obtained. 


Chapter VII. 


TRANSMITTING THE DOT AND 
DASHES OF THE DAMPED 
RADIO TELEGRAPH 


F OR those who are satisfied to listen to what others 
have to say and make absolutely no reply, a receiving 
set is all that is required. And the great majority of radio 
enthusiasts never go beyond the receiving stage, because 
they are satisfied to receive the radio-phone concerts and 
news, as well as the dot-dash messages of Government,, 
commercial and amateur stations alike. When the radio 
enthusiast desires to do a little “talking”' on his own 
account—when he tires of listening to others or when he 
wants to be able to take a hand in any discussion that 
may be taking place in the ether—he must resort to a 
transmitter of some sort or other for generating the waves 
that serve to afifect the apparatus in distant receiving sta¬ 
tions. He may wish to send in dots and dashes, or again, 
he may desire a radio telephone transmitter in order that 
he may actually talk and have his voice heard at distant 
points; but in either event he must go through the for¬ 
malities of obtaining a station license as well as an oper¬ 
ator’s license, both of which were unnecessary when he 
confined his efiforts to receiving. In this chapter we shall 
deal only with the simple radio telegraph transmitters, 
leaving the more advanced types and the continuous wave 
apparatus, which makes radio telephony possible, for the 
next chapter. Please note, however, tfiat most radio ama¬ 
teurs are now turning to the C. W. type transmitter, and 
that spark or damped wave sets must-soon become obsolete. 


206 


RADIO FOR EVERYBODY 


What the Radio Transmitter Does 


Electromagnetic waves, by means of which radio com¬ 
munication is carried on, are produced by the transmitting 
apparatus. Power must be supplied by some kind of 
electric generator or battery; this power must be converted 
into high frequency currents by means of an oscillator or 
wave generator; and the high frequency currents must 
be introduced into an aerial system consisting of the 
aerial and the ground connection, in order that the radio 
waves may be propagated in all directions through space. 

Now the radio waves, as we have already learned, may 
be of the damped or the undamped variety. Damped 





- wwwwwt 


A schematic comparison between damped and undamped 
waves. The damped waves, shown above, consist of wave 
groups or wave trains, while the undamped or CW waves 
are of uniform height and wave length and without a break. 


waves consist of groups or trains of oscillations repeated 
at regular intervals, the amplitude or voltage of the oscil¬ 
lations in each train decreasing continuously as shown in 
the accompanying diagram, where the center line indicates 
O potential, and the length of the line the lapse of time. 
The number of these waves or trains per second is some 
audible frequency. When such waves strike a receiving 
apparatus, as we have already learned, they cause a tone 
in the telephone receiver. Signals are produced by means 
of a sending key, which lets the trains of waves go on for 
a short time (producing a dot) or for a longer time (pro¬ 
ducing a dash). The operator manipulates the key in 
order to form the dots and dashes which represent the 
desired letters, numerals, punctuation and other char¬ 
acters of a dispatch. 




RADIO FOR EVERYBODY 


207 


The principles of damped and undamped waves are the 
same in many respects, so that much of what is told 
regarding damped wave apparatus applies to undamped 
waves as well. Particular attention is first given to 
damped waves, as the apparatus is simple and easily ad¬ 
justed and has long been employed. 

Damped oscillations or waves are produced when a con¬ 
denser discharges in a circuit containing inductance. The 
condenser is discharged by placing it in series with a spark 
gap and applying a voltage that is high enough to break 
down or spark across the gap. Such an arrangement is 
presented in the diagram on page 208 , where a trans¬ 
former, supplied with current from a generator or battery, 
charges the condenser placed across its terminals until the 
condenser charge has been built to a point where the spark 
gap breaks down. It is as though one were stretching a 
rubber band, thus storing up considerable mechanical 
energy, until the breaking point was reached. Then, as the 
rubber band snapped, all the stored up energy would be 
discharged. When the spark gap breaks down the pent 
up energy of the condenser is discharged. Unlike the 
rubber band, however, the charge in the condenser dis¬ 
charges across the gap and recharges the condenser in the 
opposite direction to almost the same extent as before, 
followed by another discharge which again charges the 
condenser in the original manner but of still less extent, 
followed by still another discharge, and so on with the 
current going back and forth just as does any pendulum 
which has been given a push, until its swings or oscillations 
become weaker and weaker and the pendulum comes to 
rest. 

In discharging, which only requires the fraction of a 
second, the current passes through the inductance and sets 
up electric oscillations which are damped out or, to put it 
another way, soon reach zero. These discharges, which 
follow each other in such rapid succession, form the groups 
or trains at regular intervals. 

Now the standard generator frequency for most radio 


208 


RADIO FOR EVERYBODY 


work today is 500 cycles per second. This causes the con¬ 
denser to charge and discharge 1,000 times per second, or 
once for each positive and once for each negative maxi¬ 
mum if the spark gap is of such a length as to break down 


Inductance 



The simplest kind of damped radio wave generator, consisting 
of a power source, an induction coil or transformer for stepping 
up the current, a condenser, a spark gap, and an inductance. 
The charging and discharging of the condenser through the in¬ 
ductance and across the spark gap sets up the oscillations or 

radio waves. 


at the maximum voltage given by the transformer. The 
number of sparks per second is called the spark frequency. 
With the standard spark frequency of 1,000 per second 
the amount of power the set sends out is considerably 
greater than it would be at the low rate of 60 cycles per 
second, because the transmitted radio waves are more 
nearly continuous. The radiated wave trains strike a 
receiving antenna more frequently and their amplitude 
does not need to be as great to produce the same effect as 
stronger waves received at longer intervals of time. The 
higher frequency produces a tone in the receiving tele¬ 
phones that is more easily heard, because the ear is more 
sensitive to sound waves of about 1,000 per second and 
also the tone is more easily heard through atmospheric 
disturbances. A 60-cycle supply may be used if the num¬ 
ber of sparks per second is increased by the use of a rotary 
spark gap giving several sparks per cycle, as will be 
described further on. 














RADIO FOR EVERYBODY 


209 


The Simplest of Transmitters 


Nothing could 'be simpler than the arrangement shown 
in the accompanying diagram. Indeed, in the pioneer 
days of radio such a hook-up was employed for covering 
distances up to 100 miles with a 10-inch spark coil, and 
back in the crude beginnings of amateur radio most ama¬ 
teurs made use of a spark coil and the plain aerial arrange¬ 
ment here shown. In those days the transmitters were 
gaged by the inch; that is to say, the amateur talked of 
his transmitter by referring to the sparking distance of his 
coil. Thus he had a two-inch, three-inch, ID-inch and so 
on set, according to his monetary resources or construc¬ 
tive ability as the case might be. 


I 



SG 

► 


G 


The simplest form of damped radio transmitter, consisting of 
a power source, telegraph key for making long and short 
signals of the radio code, a transformer for stepping up the 
current, a spark gap, and the aerial and the ground. In this 
arrangement, known as the plain aerial transmitter, the aerial 
and ground comprise the condenser. 

The arrangement shown in the diagram comprises a 
source of power, a means of raising the low voltage to a 
high one, say of 20,000 volts, which is sufficient to spark 




















210 


RADIO FOR EVERYBODY 


across a one-inch gap between needle points, a simple spark 
gap, a telegraph key for making and breaking the primary 
circuit, and the aerial and ground connection. When the 
key is pressed the power supply passes through the primary 
of the induction coil or transformer, as the case mav be. 
When the current is broken, or when the direction of the 
current is changed as in the case of alternating current 
which is used with a transformer, the secondary current 
flows out into the aerial and ground, which act as a con¬ 
denser, accumulating the charge. When the charge reaches 
a certain point it can no longer be contained in the aerial- 
ground condenser, and consequently it dis¬ 
charges across the spark gap, setting up 

oscillations in the aerial circuit. | I ,a 

Simple as such a system may be, it is L ——J 
hardly permissible in 

general practice for the Tunina 

good reason that the Inductance 

waves emitted are of* 

such broad wave length that they 
cannot be readily tuned out at the 
receiving end. Any amateur of 

long experience can tell you stories 




How inductance is added to vary the 
wave length of the aerial. In this in¬ 
stance the same apparatus as shown 
on page 209 is employed, but a tuning 
inductance, known as an aerial induc¬ 
tance or loading coil, is added. 


5G 


G 


of the days before the present radio laws, when it was 
possible with even a one-inch coil and other simple ap- 




















RADIO FOR EVERYBODY 


211 


paratus to prevent the most powerful stations from carry¬ 
ing on their business, if the amateur transmitter happened 
to be located a short distance away. The one-inch coil 
simply monopolized the ether in its immediate vicinity. 
It came in loudly at almost any point on the tuner, so 
that it could not be tuned out in order to receive a signal 
from a distant transmitter. However, it does not carry 
for any distance, so that outside of deliberate interference 
it was of no real value. Furthermore, one of the first 
things which the radio law accomplished was to put an 
end to these broadly tuned transmitters and in their place 
insisted- on transmitters whose emitted waves must be 
sufficiently sharp so as to have them interfere as little as 
possible with other waves. 

The plain aerial arrangement, as this layout is called, has 
other advantages aside from its simplicity. Its effective¬ 
ness comes in when the sending operator wants all possible 
stations to hear him immediately, as for instance when a 
ship is sending out a distress call. At such a time inter¬ 
ference is a desirable thing, because the distress call must 
be heard by every possible receiving station within range. 
With the regular sharply tuned waves, a receiving oper¬ 
ator may never hear the signals for the reason that his 
receiver is adjusted for another wave length and is too 
sharply tuned to respond to a sharply tuned wave. The 
broadly tuned wave, on the other hand, can be heard with 
almost any receiving set adjustment. The plain aerial has 
also a definite advantage in military activities for the 
purpose of drowning out or “jamming” the enemy’s sig¬ 
nals. For amateur purposes, however, the plain aerial 
arrangement is a thing of the past. 

A modification of the plain aerial arrangement is shown 
on the preceding page, which has a tuning inductance in 
the aerial circuit so that wave length of the emitted waves 
may be varied to some extent. Placing a condenser in the 
aerial or ground lead also varies the wave length, but 
instead of increasing it, as is the case with inductance, 
it decreases the wave length. 


212 


RADIO FOR EVERYBODY 


The Transmitting Aerial 

In transmitting- the aerial problem is far more involved 
than it is for receiving. As we have already learned, a 
single wire of almost any length or even a bed-spring 



Inverted L-type aerial, with the lead-in taken off at one end. 


or fire-escape or other mass of metal will do for an an¬ 
tenna in connection with a good receiving set, but the 
aerial of a transmitting set must be properly constructed 
if satisfactory results are to be obtained. 

To begin with, a single-wire aerial is unsatisfactory 
for transmission purposes. Two or more wires must be 
used, and four wires or more give the best results. Then 



T-type aerial, with the lead-in taken off the middle of the 

aerial span. 

the height is important; the aerial should never be less 
than 25 feet above the ground or roof, and preferably 50 
feet or more. 

In the accompanying diagrams several types of trans¬ 
mitting aerials are shown. The most common is the in¬ 
verted L-type, with the lead-in at one end. The T-type 
should be used when the span is greater than 100 feet 


















RADIO FOR EVERYBODY 


213 


in order to reduce the natural wave length of the aerial. 
The umbrella aerial should be used when one is working 
in a crowded space and there is no room for the usual 
types of aerials. The umbrella aerial makes use of a 
single tall mast, with wires radiating downwards in all 
directions. The lower ends of the wires should be at least 
20 feet away from the base of the mast. 

The construction of the transmitting aerial is consider¬ 
ably more involved than that of the receiving antenna. 
It must be larger and therefore stronger, and it must be 
better insulated because it is handling high-voltage cur¬ 
rents. The drawing on page 215 gives a few pointers 



The V-type aerial—a rare type which should only be em¬ 
ployed when a sufficient span cannot be obtained, thus mak¬ 
ing: a double aerial of this kind desirable. 


concerning the construction of a good, substantial multi¬ 
wire aerial for transmitting purposes. Note that the ends 
of each wire are insulated with hard rubber rods pro¬ 
vided with screw-eyes at each end, or with regular elec- 
trose insulators. As a further precaution, insulators may 
be inserted in the ropes or wires supporting the spreaders, 
as the sticks supporting the wires are called. Pulleys 










214 


RADIO FOR EVERYBODY 


are provided on the supports of the aerial, so that the lat¬ 
ter may be raised or lowered at will for inspection and 
repairs. Guy ropes or wires are arranged with insulators 
for the purpose of keeping the aerial perfectly flat, despite 
wind and the unequal sag of the wires. The lead-in wires 
are taken off each wire of the aerial, brought down a con¬ 
siderable distance to a point where they converge into 
one lead-in cable, just before entering the station. The 
special electrose lead-in insulator shown makes a very neat 
lead-in arrangement. It will be noted that this insulator is 
provided with a brass rod passing through it, both ends 
of the rod being equipped with nuts and lugs for making 
connections. 

The strop or egg insulator is a popular form of insula¬ 
tor for the reason that it possesses great strength and 
good insulating properties. Furthermore, in the event of 
mechanical failure, it will be noted that the two wires or 
ropes passing through different holes in this insulator 
merely come together, so that the mechanical arrange¬ 
ment still holds fast even .if the insulation arrangement 
may be broken down. 

The same aerial may be used for receiving and trans¬ 
mitting. In former days the same aerial was always used 
for both purposes. The aerial, in such a case, is designed 
with the transmitting end in view, since any good trans¬ 
mitting aerial gives good results with a receiving set. In 
order that the same aerial may be used for both purposes, 
a send-receive or aerial change-over switch is employed. 
This switch is connected with the aerial and with the re¬ 
ceiving and the transmitting sets in such a manner that 
when it is thrown one way, the aerial is connected with 
the receiving set, and is used for receiving, and when it 
is thrown the other way, it is connected with the transmit¬ 
ting set and is ready for transmitting. Obviously, it would 
not do to have the receiving set connected with the aerial 
at the same time as the transmitter, since the latter, with 
its powerful output, would cause damage to the delicate 
receiving apparatus. 


RADIO FOR EVERYBODY 


215 


Many amateurs today prefer to use. a separate aerial 
and antenna for transmitting and receiving. The aerial 
and antenna are connected with a single switching device 
in such a manner that only one of them can be used at a 



Constructional details of a good flat-top transmitting aerial, 
the strop or egg type insulator, and the electrose lead-in in¬ 
sulator. 


time, so as to preclude operating the transmitter while 
the receiving set is connected with its antenna but a short 
distance away. 

In transmitting work a good ground is necessary, for 
the best results. A ground that is imperfect or of high 
resistance will take away from the transmitting range in 
no little degree. 









































216 


RADIO FOR EVERYBODY 


Transmitters That Are Sharply Tuned 


Single-circuit transmitters are not permitted under the 
present radio laws, for the reason that 
the waves emitted are not sufficiently 
sharp. Too much cannot be said in favor 
of the radio laws in this direction; any 



Simple transmitter arrangement for producing fairly sharp 
waves of the damped variety. PS—power source; K—telegraph 
key; T—transformer; C—condenser; SG—spark gap; A and 
G—aerial and ground; and the tuning inductance or helix. 


one who has been listening in to the radio-phone service 
must have experienced the annoyance of some spark sta¬ 
tion breaking in on the music. It is only by assigning 
certain wave length bands to the various classes of trans¬ 
mitters, and insisting that their waves be kept sharply 
tuned within narrow tolerances, that interference can be 
reduced to a minimum. 

In order to emit sharp waves which come within the 
stipulations of the radio laws, it is necessary to produce 
the oscillations in a closed circuit which is directly or 
inductively coupled to the aerial or “open” circuit. Such 
an arrangement is shown in the diagram on page 217, 
where the induction coil or transformer serves to charge 
the condenser, which discharges across the spark gap and 
through the inductance. The inductance, it will be noted, 
forms part of the “closed” or oscillating circuit and also 
part of the aerial or “open” circuit. Thus it serves as 
an auto-transformer, as a single coil transformer is called. 
Any number of turns of this inductance- which is made 


















RADIO FOR EVERYBODY 


217 


up of a number of turns of heavy wire or strip, may be 
cut into the closed circuit and into the open circuit, so as 
to establish the proper ratio between the circuits. The 
positions of the spark gap and the condenser are sometimes 
interchanged, bringing the spark gap across the trans¬ 
former. There is practically no difference in the oper¬ 
ation, as a result of such a change. 

In connecting up the various components of a trans¬ 
mitting set, heavy wire, certainly not less than No. 12, 
insulated or bare, should be used. It is preferable to 
use copper strip, if possible, .since it has a greater surface 
area and the currents with w#hich we are now dealing 
travel on the suface rather than through the entire con¬ 
ductor. The conductors should be neatly run from one 
connection to the next, and arranged so as not to come 
near one another because of the danger of sparking. Fur¬ 
thermore, the conductors must be kept as short 
as possible, for in a transmitting set the induc¬ 
tance represented by a few feet of conductor 
is sufficient to make the wave . 

length of the oscillating cir- (Reluctance for 
cuit so great as to be well , Q 
beyond the permissible 200- 
meter wave length of ama- 



Short wave 
Condenser 


=T\ 


Same arrangement as shown on the fac¬ 
ing page, but with an aerial inductance 
or loading coil for increasing the wave 
length, and a ground series condenser for 
reducing the wave length, of the aerial- 
ground circuit. 




















218 


RADIO FOR EVERYBODY 


teur transmission. So the components must be placed 
close together, and connected with the shortest possible 
conductors. This also applies to the connection with the 
aerial, which should be made as short and as direct as 
possible, in order to secure high efficiency and keep within 
the wave length requirements. 

In order to determine the proper number of turns for 
the closed and the open circuits, the usual method for the 
amateur is to use a measuring device known as a hot-wire 
ammeter in the aerial circuit, for the purpose of measuring 
the aerial current. Approximate results may be obtained 
by the use of a low resistance lamp, such as a small auto¬ 
mobile lamp or even a pocket flashlamp *bulb. The lamp 
is used in place of the hot-wire ammeter, the maximum 
current in the aerial being indicated by the maxi¬ 
mum brightness of the lamp filament. If the 
current is apt to be too great for the lamp, it 



Sample spark transmitter for producing I Q 

sharply tuned waves of the damped variety. 

In this ease a transmitting eoupler or loose- — ■ ■ • 
coupler arrangement is employed, so that the —. 
oscillating or closed circuit is entirely separ¬ 
ated from the open or aerial-ground circuit. 

The primary P and the secondary S comprise 
the transmitting coupler. 


should be shunted by a few turns of wire. The ammeter 
and lamp must be eliminated or even short-circuited ex¬ 
cept when actually needed, in order to keep the resistance 
of the aerial circuit down as low as possible. 

In actual practice, the closed circuit is first adjusted to 
the desired wave length, which can best be determined by 





















RADIO FOR EVERYBODY 


219 


the use.of an instrument known as a wave meter. Then 
the aerial circuit is adjusted until the lamp or hot-wire 
ammeter indicates the maximum output, proving that the 
two circuits are in resonance. Most of the progressive 
radio clubs—and there are radio clubs in practically every 
part of the country—have wave meters for the use of their 
members. The best method of tuning, aside from waiting 
for the radio inspector to tune the transmitter when he 
comes to inspect it, is to call upon the local radio club for 
aid in this direction. 

One method largely employed by amateurs in tuning 
their transmitters is to adjust their oscillating circuit and 
then the aerial circuit for maximum output, after which 
they ask a radio friend to listen in on his receiving set to 
the test signals and to determine whether they are higher 
or lower in wave length than those of other amateur sta¬ 
tions known to be tuned to a wave length below 200 
meters, which is the maximum set for amateur transmis¬ 
sion. This latter method, however, is not very accurate. 

In most instances it is best to wait until the radio inspec¬ 
tor comes to the station in order to check up the trans¬ 
mitted wave length. The inspector, being provided with 
a wave meter, sees to it that the station is emitting a wave 
within the set limits and also that the wave is sufficiently 
pure or sharp to comply with the law. 

At this point it is well parenthetically to point out that 
the transmitter problem may be materially simplified by 
purchasing a complete transmitter in one unit. Today the 
practice is to make the transmitter apparatus into one 
simple unit in the form of a panel, the controls and 
meters being placed on the front face, and the various 
components at the rear. Such a transmitter has wave 
length adjustments and hot-wire ammeter, as well as other 
controls which simplify the tuning and general operation. 

If a complete transmitter is not employed, then it is 
necessary to purchase separate pieces of apparatus and to 
arrange them in some suitable manner. Any radio supply 
house will gladly furnish the necessary technical assistance 


220 


RADIO FOR EVERYBODY 


in the installation of a radio transmitter. Then again, if 
one has cultivated the friendship of the radio amateurs 
in the general vicinity, one can obtain all the necessary 
help in this direction. 

So much for the directly-coupled set which we have so 
far discussed, and the tuning of a transmitter. There is 
another arrangement known as the loose-coupled set, which 
is shown in the diagram on page 219. Here the closed 
and the open circuits are not connected directly, but are 
inductively coupled. Such an arrangement makes for 
sharper waves and a high degree of efficiency. The 
coupling may be varied so as to obtain the best results, the 
adjustment depending largely on the type of gap employed. 

The Question of Transmitting Condensers 

The most common types of condensers used in radio 
transmitting circuits employ mica or glass as the dielectric, 
with tinfoil or thin copper as the conducting coatings. 
Compressed air and oil condensers are sometimes used in 
professional work, but they are balky and certainly well 
outside of the province of the amateur. For very high 
voltages the condenser plates are sometimes immersed in 
oil to prevent brush discharge. Brush discharge is the 
leakage of current which takes the form of tiny purple 
streamers or sparks about the edge or any conductor of 
high voltage current. For moderate voltage a coating of 
paraffin over glass plates, especially at the edges of the 
metal foil, will satisfactorily reduce brush discharge. 
Today, however, the amateur is indeed fortunate in that 
his condenser problem is solved by purchasing one or the 
other of the several manufactured condensers which come 
in compact molded units, or in wooden or metal cases. 
A condenser of suitable size can be obtained in one unit 
or built up of several units. 

The transmitting condensers mostly used today are of 
the mica insulated type. These condensers have been 
found to be superior to any other type. Each mica con¬ 
denser is composed of several sections or units enclosed 



INDICATING 
I NSTRUMENTS 


MOTOR-GENERATOR 
OINTROLS 


COUPLING 

CONTROL 


WAVE LENGTH 
CONTROLS 


QUENCHED GAP 


POWER CONTROL 
PANEL 


Panel type damped wave transmitter, such as is employed on 
hoard steamers. This transmitter makes use of a quenched gap, 
which is mounted on the front of the panel. (See page 223. i 


















222 


RADIO FOR EVERYBODY 


in a common casing of aluminum or wood, depending upon 
the capacity and voltage. Each of these sections or units 
comprises alternating sheets of mica and foil, over a 
thousand in number. The sections or units thus . con¬ 
stituted are piled on top of one another in the aluminum 
casing, and each section or unit is separated from the 
next by a sheet of mica. The sheets of mica are larger 
than the sheets of foil, so as to avoid any brush discharge 
at the edges. 

Air, moisture, and small vacuum pockets must be elimi¬ 
nated from each section or unit, hence an insulating ad¬ 
hesive of special composition, having the required dielec¬ 
tric properties, is forced through the entire condenser. 
The moisture and air are expelled, and the vacuum pockets 
are filled with this adhesive, which is deposited in a thin 
layer on each of the thousand sheets of mica. Next a 
melted wax compound is poured into the aluminum casing, 
so as to fill any empty spaces between the condenser sec¬ 
tions or units and the case. 

Before the wax has hardened a pressure plate is placed 
on the topmost section or unit. After the cover is screwed 
on, this plate presses all the sections together. Because 
they are pressed together, the sections cannot move about. 
It is highly important that the spacing between the metal 
foil and the mica be kept constant—an end secured by the 
use of the pressure plate. A post passes up through the 
cover of the case and serves as one terminal, the case 
serving as the other when metal is used for the case. 

The efficient use of the space inside the condenser— 
the active surfaces taking up the larger part of this volume 
—is, of course, a big factor in making the mica condenser 
a fractional part of the size of the glass plate or Leyden 
jar condensers of equal capacity. The Leyden jar con¬ 
densers are the bottle-like contraptions with an inside and 
outside tinfoil coating, seen in physics laboratories and in 
connection with X-ray and electro-therapeutic apparatus. 
Yet the mica condenser has 2,000 square inches of active 
surface as compared with 175 square inches for a glass 
dielectric condenser of equivalent capacity and voltage. 


RADIO FOR EVERYBODY 


9 0 Q 

/v <v O 


Since the mica condenser consists of over a thousand 
sheets of mica and foil, the full voltage across the trans¬ 
former is minutely subdivided. Etence the potential that 
does act across a single unit is so very small that there is 



Panel type damped wave transmitter, the front view of which 
appears on page 221. Simple as the front view may seem, it 
will be noted that the transmitter is quite complicated with most 
of its mechanism mounted at the rear of the panel. 










224 . 


RADIO FOR EVERYBODY 


no destructive brush. The losses m the dielectric increases 
greatly with the voltage. Therefore, if the voltage of 
each section in the condenser is reduced markedly, the 
problem of preventing the brush discharge is met. It is 
better to control several hundred volts in this manner than 
twenty-thousand volts individually. 

When the spark gap of a transmitter is broken down by 
the high voltage it becomes a conductor, and readily allows 
the oscillations of the condenser discharge to pass. Dur¬ 
ing the interval between discharges the gap cools off and 
quickly becomes non-conducting again. If the gap did 
not resume its non-conducting condition, the condenser 
would not be charged again, since it would be short- 
circuited by the gap, and further oscillations could not be 
produced. The restoration of the non-conducting state is 
called “quenching.” A device called the quench gap is 
described further on. 

Spark Gaps of All Kinds 

A plain spark gap usually consists of two metal rods so 
arranged that their distance apart is closely adjustable. 
The gap must be kept cool, so that the discharge will not 
arc and to this end the rods are often provided with cooling 
fins. The length of the gap which can be employed is 
limited by the voltage that the transformer is capable of 
producing, the ability of the condenser dielectric to with¬ 
stand the voltage, and the fact that for readable signals 
the spark discharge must be regular. If the gap is too 
long, sparks will not pass, or only at irregular intervals. 
If the gap is too short, it may arc and burn the electrodes. 
Even if no arc takes place, the voltage is reduced by too 
short a gap and this results in reduced power and range. 
The length for smooth operation can usually be determined 
by trial. 

It is found that a short gap between cool electrodes is 
quenched very quickly, the air becoming non-conducting 
almost immediately after it has broken down, or as soon 
as the current falls to a low value. This action is also 
improved if the spark gap is enclosed in an air-tight cham- 



POWER SUPP 
AND AERIAL 
AMMETERS 


AERIAL INDUCT¬ 
ANCE CONTROL 


WAVE LENGTH 
CONTROL 


SPEED AND VOLT¬ 
AGE CONTROL 


COUPLING 

CONTROL 


QUENCHED 
SPARK* GAP 


MOTOR- 
GENERATOR 
CONTROL 
PANEL 


■ 

i 

■ 

i 


J 


Another type of damped wave transmitter, sneh as is used on 
board ship. In this instance there are two methods of obtaining: 
the oscillations or waves. There is the quenched grap mounted 
on the front of the panel, and the synchronous rotary gap 

mounted at the right. 











226 


RADIO FOR EVERYBODY 


ber. The standard form of quenched gap, as such a gap 
is called, consists of a number of flat copper or silver 
disks of large area, say three or four inches in diam¬ 
eter at the sparking surfaces, with their faces separated by 
a space about the thickness of a piece of heavy paper. To 
provide the necessary total length of gap for high voltage 
charging, a number of these small gaps are put in series, 
so thaf the spark must jump them all, one after the other. 
The disks are separated by rings of mica or paper. The 
larger gaps handling considerable power are kept cool by 
means of a small fan or blower. But all quenched gaps 
are provided with projecting fins for radiating heat, and 
in some designs air spaces are provided between the pairs 
of disks which form the successive gaps. The number of 
gaps is determined by the voltage, allowing about 1,200 
volts per gap. Eight or ten gaps are sufficient in most 
transmitters of this type. 

The quenched gap is not used in sets having a supply 
frequency as low as 60 cycles per second. The sparks 
obtained at that frequency are found to be irregular and 
not of a good tone. For this case, a rotary gap is used, 
as will be explained. For 500-cycle supply the quenched 
gap is adjusted to break down at the maximum value of 
the applied voltage; that is, with its total length so ad¬ 
justed as to give one spark for each half cycle of the 
applied current. Discharges at other times are not pos¬ 
sible, and as a result of this regularity a clear note is 
obtained. One advantage of the quenched gap is that it 
.aids the production of a so-called pure wave—one which 
is sharply tuned. It has also the advantage of being noise¬ 
less in operation, on account of the very short gaps and the 
•enclosure of the spark. 

A 500-cycle current supply may be obtained by using 
what is known as a motor-generator—a motor operating 
off the usual supply current, directly connected with a 
500-cycle alternating current generator which supplies 
•current for the radio transmitter. Such motor-generator 
sets may be obtained in a wide range of capacities for 
the smallest as well as the largest transmitters. 


RADIO FOR EVERYBODY 


227 


A rotary gap consists of a wheel with projecting points 
or knobs, with a stationary electrode on each side of the 
wheel. The spark jumps from one stationary electrode 
to one of the moving points, flows across the wheel, and 
then, after leaping the corresponding gap on the other 
side, passes out at the second stationary electrode. The 
number of sparks per second is thus determined by the 
speed of the wheel which is motor-driven, so that signals 
of high pitch can be produced. An advantage of the 
rotary gap is the prevention of arcing, because of the 
motion of the wheel and the fanning effect, and because 
the electrodes brought successively up to the spark gap 
have time to cool in their idle intervals. 

There is still a more elaborate form of spark gap which 
is seldom found in amateur work but which might as well 
be mentioned here, since we have covered practically all 
forms of transmitters of the damped wave category. This 
more elaborate form is known as the synchronous rotary 
gap. The wheel of the rotary gap is mounted on the shaft 
of the motor-generator set which furnishes the alternating 
current. The mounting is such that the spark points or 
electrodes are brought opposite each other at just the mo¬ 
ment when the alternating current voltage in the condenser 
reaches its maximum value, positive and negative. Thus 
500 cycles will produce 1,000 sparks per second. This 
regular occurrence of the discharges gives smooth and 
efficient operation, as well as a pure musical tone. A 
rotary gap that is not so timed with the alternating cur¬ 
rent supply is called non-synchronous. 

Attempts to produce a high pitch spark with a 60-cycle 
source by means of a synchronous gap giving, say, exactly 
six sparks per half cycle have not given satisfaction, be¬ 
cause the applied voltage is not the same at the time of 
the different sparks, and while the note is of high pitch, 
it is not musical. It has been found better to use a non- 
synchronous gap in such case, producing a large number 
of sparks per second and letting them occur wherever 
they may happen during the cycle. The irregularities will 


228 


RADIO FOR EVERYBODY 


somewhat balance up. While the tone is not strictly musi¬ 
cal, it can be made of high pitch. The non-syncnronous 
gap is best used if nothing but a 60-cycle or other low 
frequency source is available. Such a low frequency, 
however, is being avoided in modern apparatus, the stan¬ 
dard frequency being 500 cycles per second. But for the 
amateur who cannot go to the expense and trouble of a 
small motor-generator set for generating a 500-cycle cur¬ 
rent, the rotary gap will be found quite satisfactory on 
60-cycle supply. 


Chapter VIII. 


THE RADIO TELEPHONE TRANSMIT¬ 
TER AND THE CW TELEGRAPH 
TRANSMITTER 



HE transmitters described in the previous chapter are 


JL of the damped or discontinuous variety. They are 
suitable for radio telegraph purposes, although the con¬ 
tinuous or undamped wave type has proved to be so much 
better than the former that more and more radio amateurs 
have turned to this latter method. The continuous wave 
transmitter carries farther with a given amount of power; 
the equipment is in many respects simpler; it is silent in 
operation; it can be interchangeably used for radio tele¬ 
graph or radio telephone. 

We have already learned that damped waves are sent 
out in trains or groups, and that the oscillations in each 
train or group die down or are damped rapidly. The un¬ 
damped or continuous waves, known as CW for short, 
are not damped, nor do they die down. The waves are 
continuous just so long as the transmitter is operated. 
The only change in the amplitude or potential of the waves 
is when they are modified by means of a telegraph key to 
form the dots and dashes of the telegraph code, by means 
of a buzzer to give what is known as modulated C. W., 
or by the voice modulations for radio telephony. 

The Vacuum Tube in a Transmitting Role 

Thanks to the recent development of the vacuum tube 
as a generator of high frequency oscillations, it now 


230 


RADIO FOR EVERYBODY 


becomes possible to produce continuous oscillations or CW 
on a small as well as large scale. This fact has resulted 
in the production of compact, continuous wave transmit¬ 
ters which may be used for radio telephony or radio 
telegraphy by the amateur. In fact, at this writing the 
CW transmitters now being offered are no more compli¬ 
cated in their operation than the receiving sets; in truth, 
at a glance one could not tell a small CW transmitter apart 
from a vacuum tube receiving set. 

Let us consider a typical radio telephone and telegraph 
transmitter now on the market. All the controls and 
apparatus necessary to operate this transmitter are mounted 
on two panels, each measuring 9 inches by 4^2 inches. 
The left panel contains the grid, plate, and the antenna 
inductances and their control switches; a compact induc¬ 
tance unit serving as a choke coil; a send-receive transfer 
switch; and variable antenna condenser. The right-hand 
panel contains tube receptacles, standard modulation trans¬ 
former, filament rheostat, radiation ammeter, grid leak, 
grid stopping condenser, and filament insulating condenser. 
These various terms will become clearer as we read more 
about the elements of a CW transmitter. 

Using a 100-volt “B” battery on the plates, this set 
radiates .1 to .2 ampere and the range is 10 to 15 miles. 
With 350 volts impressed on the plates .3 to .4 ampere will 
be radiated, giving a range of 25 to 30 miles. With 500 
volts plate voltage, the aerial ammeter reading will be 
.5 to .6 ampere, or sufficient to cover 35 to 50 miles. 

By the addition of a buzzer and key, modulated con¬ 
tinuous wave transmission is possible and the above ranges, 
which are for the radio-phone, are doubled. Adding a 
key only, provides continuous wave communication, trip¬ 
ling the ranges. However, with the key only, the waves 
are absolutely continuous, or what, is known as straight 
C W, and do not serve quite as well for amateur purposes 
as the interrupted or modulated CW, which may be de¬ 
tected with any type of receiving set within range. The 
straight continuous wave can only be detected with a 


Amateur continuous wave transmitting station, showing the arrangement of the various transmitting and 
receiving instruments. The CW transmitting apparatus is more compact and neat, let alone less troublesome 

than the damped spark transmitters. 
















232 


RADIO FOR EVERYBODY 


receiving set intended for and adjusted for continuous 
wave reception, as explained in previous chapters dealing 
with receiving sets. 

A six-volt storage battery lights the filaments and pro¬ 
vides current for the microphone, while the plate current 
can be obtained from a rectifier unit and transformer 
operating on alternating current supply, or any motor- 
generator set. Any manufacturer of radio-phone trans¬ 
mitters will explain just what equipment and accessories 
are required for this kind of work. It is too involved 
to be treated in this popular work. 

Then there are the larger types of radio-phone trans¬ 
mitters. A relatively simple cabinet set, with a panel 
measuring 13 inches by 11/4 inches, and 8 inches deep, 
may be relied upon for uninterrupted, dependable trans¬ 
mission over distances up to 60 miles. Variable controls 
have been reduced to a minimum and operation could not 
be further simplified in many of the offerings of this class. 
On the face of the panel are the plate current milli-am- 
pere radiation meter, two filament rheostat knobs, the 
send-receive switch, a switch for changing from speech to 
modulated CW or straight CW, antenna condenser switch 
and motor control switch. On the rear of the panel are 
filter condenser, constant current coil, high frequency 
choke coils, grid condenser, plate condenser, filament in¬ 
sulating condenser, antenna condenser, grid leak, four tube 
receptacles, modulation transformer, antenna inductance, 
and microphone resistance. 

To supply the plates with a potential of 350 to 500 
volts, a 32 or 110-volt dynamotor (a single motor and 
generator unit) or a 32 or 110-volt motor-generator (a 
motor and a generator connected together) is required, 
while for the filaments and microphone a 10-volt storage 
battery is necessary. The 32-volt potential is mentioned 
because certain rural districts make use of this low voltage 
in their isolated plants that supply lighting current. 

So much for the complete sets of low and moderate 
power. When it comes to more ambitious ranges, running 
into the hundreds of miles, a much larger transmitter 


RADIO FOR EVERYBODY 


233 


must be considered. Following the panel idea, there are 
one-half, one-kilowatt, two-kilowatt, and larger CW 
telegraph and telephone transmitters. The various con¬ 
trols and meters are mounted on the panel, while the 
various components are mounted at the rear, both on the 
reverse side of the panel and on iron brackets and shelves. 

Why CW is Popular 

In time it is believed that virtually all radio amateur 
stations and, for that matter, commercial stations, will 
be using CW or undamped wave transmitters for these 
reasons: 



Typical radio-phone transmitter, which is provided with 
rectifying tubes so that it can be operated on an alternating 

current lighting circuit. 


(1) Radio telephony is made possible on a small or 
large scale. (2) Extremely sharp tuning is obtained and 
consequent reduction of interference between stations 
working close together. A slight change of adjustment 




234 


RADIO FOR EVERYBODY 



Typical CW transmitting equipment, showing its simplicity. 

The coil at the left is a grid coil, while the instrument at 
the right is a transmitting helix, made up of a number 
of turns of flat copper strip. The clips are for the purpose 
of making the necessary connections at any points on the 
helix in order to obtain the proper wave length values. 

throws a receiver out of tune, and the operator may pass 
over the correct tuning point by too rapid a movement of 
the adjusting knobs, so sharp is the continuous wave 
transmitter. (3) Since the oscillations go on continuously 
instead of only a small fraction of the time, as in the 
case of damped waves, their amplitudes need not be so 
great and hence the voltage applied to the transmitting 
condenser and aerial arg much lower. This means that 
the problem of installation is reduced to a minimum and 
the installation of such a set is made relatively simple. 
(4) With damped waves the pitch or tone of received 
signals depends wholly upon the number of sparks per 
second at the transmitter. With undamped or continuous 
waves the receiving operator controls the tone of the re¬ 
ceived signals, and this can be varied and made as high or 
as low as possible in pitch to distinguish the signals from 































RADIO FOR EVERYBODY 


235 


atmospheric disturbances and to suit the pitch to the 
operator’s ears and to the sensitiveness of the telephone 
receivers. These advantages, freedom from interference 
caused by other stations, the use of high tones and low 
voltages, and the greater freedom from strays combine to 
permit a higher speed of telegraphy than could otherwise 
be obtained. 

How CW Transmitters Work 

Persistent, continuous or undamped waves, whichever 
you wish to call them, can be generated by several distinct 
methods, each having its advantages and disadvantages, as 
follows: 

(1) 'The arc or Poulsen method, so named after its 
Danish inventor. Oscillations of radio frequency are 



A 50-watt transmitting tube, showing its principal elements. 
Like the amplifier and detector tubes, it comprises a filament, 

grid, and plate. 















236 


RADIO FOR EVERYBODY 


obtained by means of an electric arc burning in an atmos¬ 
phere of hydrogen and in a strong magnetic field. The 
arc method produces undamped waves of rather long wave 
length, and is ordinarily operated on 500 volts direct cur¬ 
rent. It has been discovered that an electric arc between 
proper electrodes, shunted by an inductance and a con¬ 
denser, will produce continuous oscillations through the 
shunt circuit, and such a circuit is used to excite an aerial 
circuit for transmitting purposes. Depending on whether 
a telephone microphone or key is employed, the arc gen¬ 
erator may be arranged for radio telephony or telegraphy. 
Needless to say, the arc is unsuitable in many ways for 
amateur radio purposes, because it is too elaborate to 
begin with, the oscillations are of too great a wave length, 
and the arc cannot be constructed for small powers yet 
produce efficient results. 

(2) The high frequency alternator method, which is 
practically an alternating current generator of special de¬ 
sign having a great number of poles revolving at a high 
speed, in order to obtain the necessary high frequency. 
A standard General Electric Company two-kilowatt high 
frequency alternator designed for a frequency of 200,000 
cycles or 1,500 meters wave length must be revolved at a 
speed of 20,000 revolutions per minute. This is a very 
high rate of speed. Imagine a speed seven or more times 
as fast as the turning of the average electric fan! Again, 
needless to say, this is not a good method for the average 
amateur. 

Skipping over several other highly technical methods, 
we come to the vacuum tube oscillator method, which is 
brought about by using what is known as the Armstrong 
“feed back” or regenerative system, which has already 
made our acquaintance in the previous chapters dealing 
with receiving systems and methods. This kind of CW 
transmission is brought about by placing an inductance 
in series with the plate, and this, in turn, is placed in 
inductive relation with the grid, causing the plate current 
to act on the grid and producing oscillations of a frequency 


A compact CW transmitting set complete with storage battery and high voltage dynamotor. Sets of this kind have 
been developed for airplane use, where every ounce of weight counts. The key, shown in the left foreground, is 

of the non-arcing type, so as to minimize danger aboard airships. 










238 


RADIO FOR EVERYBODY 


dependent entirely on the constants or electrical values of 
the circuit. Perhaps the accompanying diagram makes 
the foregoing description clearer. It will be noted that the 
arrangement here shown is very much like the usual regen¬ 
erative receiving hook-up, except that the telephone re¬ 
ceivers have been left out, and a telegraph key is placed 
in the primary circuit of the oscillation transformer or 




Simple CW telegraph transmitter which 
may be assembled by any one. A—aerial; 
(1—ground; P and S—primary and sec¬ 
ondary of the loose-coupler LC; VC1— 
variable condenser for reducing wave 
length of aerial-ground circuit if neces¬ 
sary; VC2 —variable condenser; OT—oscil¬ 
lating tube; A—filament battery; R—fila¬ 
ment rheostat; It—filament battery; F— 
feed-back or tickler coil. 


transmitting loose-coupler in such a manner as to short- 
circuit several turns every time it is pressed down. This 
causes the wave length to. fluctuate, and produces the dots 
and dashes in the sharply tuned continuous waves inter¬ 
cepted at the receiving end. 

The experimenter is practically limited to the vacuum 
tube for his experiments and work with undamped waves 
because of the cost and other deterrent features of other 
























CHOPPER 


POWER 

CONTROLS 


VACUUM TUBES 


INDUCTANCE 

UNIT 


WAVE LENGTH 

CHANGING 

OEAR 


Mechanism of a commercial CW telegraph transmitter, using 
several 50-watt tubes and a chopper for producing modulated 

continuous waves. 


















240 


RADIO FOR EVERYBODY 


systems. Even leaving aside the consideration of cost, 
in most instances the undamped wave generators other 
than the vacuum tube operate best on long wave lengths 
which are barred to the amateurs. However, the fact 
remains that the vacuum tube makes an excellent generator 
—one that is quite flexible, too, since its power can be 
increased merely by connecting more bulbs in parallel.. 

Placing the key across a few turns of the oscillation 
transformer, so that the CW transmitter is tuned and 

detuned with the 
operation of the key, 
is often done. It will 
be recalled that the 
sharpness of u n - 
damped waves is quite 
marked at the receiv¬ 
ing end, so that it fol¬ 
lows that when the set 
is detuned, even to 
the extent of two 
turns of the secondary 
of the oscillation 
transformer, the 
waves are not heard 
at that moment. In 
this manner it is pos¬ 
sible to make dots and 
dashes with an or¬ 
dinary telegraph key 
even when handling considerable transmitting power, since 
little power is broken by the contacts. 

Another method of CW transmission is to use mod¬ 
ulated persistent waves by having a transformer in the 
grid circuit and a buzzer and key in the primary winding 
of same, as shown in the accompanying diagram. The 
note emitted is similar to the tone of the buzzer used, and 
such signals can be received on any type of receiving set 
as distinguished from the straight CW waves which 


v- 


^i|iMeseK» 





Simple method of producing: 
buzzer modulated CW waves. 
Note the buzzer inductively 
•M't'I'l connected with the grid cir¬ 
cuit. A—aerial; VC1—vari¬ 
able condenser in aerial- 
ground circuit; VC2—vari¬ 
able condenser in oscillating 
circuit; R—filament rheostat; 
A —filament battery ; B—plate 
battery. 



























RADIO FOR EVERYBODY 


241 


cannot be heard with the ordinary crystal detector working 
in a damped wave receiving circuit. 

What is known as a chopper is also used to break up 
the continuous waves in order to make them audible with 
any type of receiving set. The chopper is simply a motor- 
driven commutator or circuit breaking device, which breaks 
a circuit a given number of times according to the speed 
at which it is revolved. The chopper can be placed in 
series with the grid resistance and its rate oi rotation will 
then determine the note of the CW signals, and make them 
audible to any receiving set. 

The matter of the aerial is a very important consider¬ 
ation in CW transmission, for the reason that the waves 
are so sharply tuned that the slightest change in wave 
length affects the reception of the waves. Thus if the 
aerial should sway with the wind and change the distance 
between its wires and the ground, the wave length of the 
transmitted waves will also be varied, ever so slightly to 
be sure, but enough to give some trouble at the receiving 
end. 

For this reason special aerials are often used in C W 
transmission. Instead of using the flat-top aerial, with 
•the wires side by side supported on spreaders at either 
end, the cage type of aerial is often employed. This 
aerial has hoops or rings at each end instead of the usual 
spreaders, and the wires are arranged on these hoops or 
rings so as to form a round or cage-like aerial which is 
supported in the usual manner. The cage type of aerial 
is more Constant in its electrical characteristics and is 
therefore more satisfactory in CW work. Furthermore, 
to ensure still greater rigidness, the counterpoise form 
of ground is also employed to a large extent in CW trans¬ 
mission. 

The necessity for a rigid aerial system is, obviously, 
more essential when the dots and dashes or the telephone 
modulation is obtained through a change in wave length, 
than when the dots and dashes and telephone modula¬ 
tion are caused by a change in amplitude or voltage. 


243 


RADIO FOR EVERYBODY 



HV telegraph and radio-phone transmitter of the panel type, 
with the various controls and meters mounted on the front 
face. Transmitters of this type are being used in several of 
the radio-phone broadcasting stations. 

The general subject of CW transmitters is such a large 
one that we cannot afford to go deeper into it at this time. 
Then again, it is very well covered by more advanced 
works, and certain radio companies have brought out ex- 












RADIO FOR EVERYBODY 


243 


ceptionally complete and explicit literature on CW trans¬ 
mission. 

Radio Telephony Reduced to its Simplest Form 

If one is satisfied with a range of but a few miles, a CW 
transmitter may be readily assembled, and it can be almost 
as easily used for radio-phone work as for radio telegraph. 

First of all, the radio amateur must obtain the proper 
vacuum tube. So far we have spoken of the vacuum 
tube detector and the vacuum tube amplifier tubes, but 
now we come to the 
transmitting tubes. 

The standard trans : 
mitting tubes now 
available on the mar¬ 
ket come in 5-watt, 

50-watt and 250-watt 
sizes. For our pres¬ 
ent purpose the 5- 
watt is the most pop¬ 
ular, since we are 
dealing with low 
power. Two 5-watt 
tubes in parallel will 
put from one and 
one-quarter to one 
and three-quarter am¬ 
peres in the amateur’s 
aerial. Using one of 
these tubes as a mod¬ 
ulator and the other 
as an oscillator, for 
experimental radio 
telephony, distances 
up to 40 miles can be 
covered, an/d at least four times that distance when the 
two tubes are connected in parallel for CW telegraphy. 
Four or five 5-watt tubes can be worked in parallel with 
increased range. The 5-watt tubes are also used as power 



A simple continuous wave telegraph 
transmitter, making use of a single 
5-watt tube. This set transmits 
straight CW. A—aerial; I—aerial in¬ 
ductance ; B—high voltage battery; 
VC1—variable condenser; G—ground; 
K—telegraph key; VC2—grid conden¬ 
ser; OT—oscillating tube; A—filament 
battery; R—filament rheostat. 
















244 


RADIO FOR EVERYBODY 


amplifiers in radio receiving circuits. The energy ampli¬ 
fication obtained therefrom is particularly useful for the 
operation of loud-speakers. 

___ The 50-watt transmitting tube is intended for 
\ / long-distance telephony and telegraphy. Two 
t A 50-watt tubes connected in a self-rectifying 

or in a straight direct-cur¬ 
rent plate excitation cir¬ 
cuit will give aerial cur¬ 
rents of three to four am¬ 
peres at amateur wave 
lengths. A single tube 
operated from a direct- 
current source or a recti¬ 
fied alternating cur¬ 
rent source will put 
two and a half to 
three amperes in the 
amateur’s aerial. 
Hundreds of these 
tubes are already in 


B H 



TR Hx 


(' I'lM'l Q 


Simple combination 

radio telegraph and nse in amateur trans¬ 
radio-phone trans- mitting Stations 

I—aerial inducting’; throughout the COUn- 

B—high-voltage bat- f r j U.Vfanrpg 
tery; VC1—variable dncl CUSianceS Up 

condenser; TR —telephone microphone; to 1 900 miles have 
VC2—variable condenser; K—telegraph .. ’ , . 

key; OT—oscillating tube; A—filament been COVered by USing 
battery; R—filament rheostat. in an appropriate Os¬ 

cillating circuit. 

The 250-watt tube is the most powerful tube of the 
series now on the market for experimental and general 
transmission purposes. This tube is equipped with a spe¬ 
cial filament which gives exceptionally long operating life. 

Let us return to the 5-watt tube and to the simple trans¬ 
mitter, which is more in the province of this book than 
the more powerful, more elaborate transmitters. A simple 
radio-phone transmitter may be readily built or rather 
assembled by the radio enthusiast, who wishes to do a 















RADIO FOR EVERYBODY 


245 


little talking on his own account and is willing and ready 
to secure his operator’s and station licenses. 

The first step is to obtain a 5-watt transmitting tube. 
Then we need two 22^2-volt B battery of the same kind 
as we used for the receiving sets. On one battery a 5- 
watt tube, under good conditions, will transmit 5 to 10 
miles. Then we need a variable condenser of 0.001 mfd. 
maximum capacity, which is connected in the ground cir¬ 
cuit, and another variable condenser with a maximum 
capacity of 0.0005 mfd. which is placed in the grid circuit. 
A suitable 'CW helix or inductance is also required. This 
last-named piece of apparatus may be purchased already 
made, or it can be constructed of heavy copper wire made 
into a coil with the turns separated % to l / 2 inch apart. 
Clips are used to make connections with any desired part 
of the helix or inductance. A six-volt storage battery, 
vacuum tube socket, filament rheostat, and a 
telegraph key complete the outfit. A micro- 
^ phone can be substituted for the key and the 
set converted into a short-distance telephone 
transmitter. If possible, a hot wire ammeter 

should also be included 
with the set. This instru¬ 
ment is placed in the 
ground lead and serves to 


v. 


61 



rwFi g 


How two or three tubes may be arranged 
in parallel for obtaining greater power 
while still using the same simple arrange¬ 
ment. In this ease straight CW telegraph 
is obtained. 

























246 


RADIO FOR EVERYBODY 


indicate when the transmitter is adjusted to maximum 
efficiency. 

Tuning the set is accomplished in very much the same 
manner as with the damped wave transmitter. With the 
filament of the tu'be lighted and the set oscillating properly, 
the series and the grid condensers are varied until a max¬ 
imum output is indicated by the ammeter. However, 
this method does not indicate just what the wave length 
may be, and one may be overstepping the 200-meter limit. 
It may be well to have nearby amateurs listen in and say 
whether the emitted wave appears to be below 200 meters,, 
and also when the transmission is at its best. 

The output of the transmitter can be increased by using 
a higher voltage on the plate. By means of additional 
B battery units, the voltage can be increased to 90 volts. 
It must be remembered in this connection that the energy 
for the waves is taken from that source. Just so long as 
the tube does not glow with a blue haze, the B battery 
voltage can be piled on, increasing the efficiency and the 
range. Another scheme is to use two or three tubes in 
parallel, with the grids connected together and also the 
plates. Only one B battery is required for all the tubes. 

Much could be said here regarding modulator tubes, 
which permit of modulating heavy transmitting currents 
by means of ordinary carbon microphones through the 
medium of vacuum tubes known as modulator tubes, and 
magnetic modulators. Then there are filter reactors, rec¬ 
tifiers, filters, microphone transformers, and other devices 
which enter into the more elaborate CW transmitters, but 
for further information along these lines we must look 
to more advanced works specializing in CW transmission. 


Chapter IX. 


THE UNUSUAL USES OF RADIO ON 
LAND AND SEA AND IN THE AIR 


R ADIO has many uses aside from the broadcasting of 
entertainment and news and the linking of widely 
separated points. In fact, it seems as though we have 
done little more than scratch the surface of its vast pos¬ 
sibilities, and that the inventive talent of today must lead 
us to still greater and more startling achievements in the 
application of radio. 

In the early days of radio, too much was expected of it. 
There was much promise of the transmission of power 
by radio in order that airships and automobiles and street 
cars and ocean liners might be operated by distant power 
plants without the agency of wires or cables. Yet we 
know today that the transmission of power by radio is still 
a remote possibility; we know that, starting with one kilo¬ 
watt at the transmitting end, we obtain less than a thou¬ 
sandth of a watt, or one millionth of the original power 
expended at the receiving end. The radio method of 
transmitting power is a most inefficient one, and only if 
we hit upon some entirely new principle of transmission 
and reception can we hope to make anything of the idea 
of radio transmission of power. 

However, whatever radio wonders may have been ex¬ 
pected in the early days have been more than realized, 
even though the present achievements may be along en¬ 
tirely different lines. 


248 


RADIO FOR EVERYBODY 


The Marvels of Radio Control 

One of the most promising fields of unusual radio, if 
we may call it such, is the one given the broad name of 
radio control. This means the controlling of machinery 
and other things at a distance through the use of radio. 
Thus small vehicles and boats controlled by radio have 
attracted no little attention wherever they have been 
shown. 

Mysterious as these things may be, there is really 
nothing very complicated about them. This does not mean 
to say that anyone can construct a successful radio- con¬ 
trolled car or boat with little trouble, because there is 
a good deal of experimental work to be performed before 
such a delicate assembly can be made to work properly; 
but the principles are public property and may be em¬ 
ployed by anyone of an inventive turn of mind. 

The principle of radio control rests on the transmission 
of certain signals or radio waves which affect a detector 
in the same manner as themsual receiving set. Instead of 
rectifying the intercepted wave energy for a pair of tele¬ 
phone receivers or for a loud-talker, however, the detector 
in this case passes its output over to a delicate relay, 
which is a device that is actuated by a source of delicate 
current so as to open and close the circuit of a more 
powerful local current. The more powerful current can 
therefore be made to do whatever work is desired. So, if 
we press the key of a transmitter, tuned to the right 
wave length, the machinery to be controlled intercepts 
the signal and operates its relay, which in turn closes the 
local current circuit for the performing of any desired 
task. However, such a simple system gives only one com¬ 
mand, so to speak, and since a number of different tasks 
must be commanded by means of the remote control, some 
other agency must be introduced of multiplying the num¬ 
ber of commands that can be issued. 

There are several ways in which a number of different 
things can be commanded or controlled by remote control. 
The simplest method is to use a revolving contact drum, 


The radio-phone in the typical American home. The loud-speaker used in this instance makes it possible 
to enjoy the radio-phone concerts and talks without the necessity of wearing head receiver, except for 

accurate tuning and long distance work. 







250 


RADIO FOR EVERYBODY 


as it is termed, on which are arranged metal strips which 
can make various combinations of electrical connections 
and which come into action one by one as the drum is 
revolved. This drum is revolved continuously at a pre¬ 
determined speed, or step by step. In the latter case one 
combination of connections after another is brought into 
action by means of an electro-magnetically operated 
ratchet device, which functions through the closing of the 
relay contacts. Every time a signal is sent out by the 
transmitter, the relay of the receiving device closes the 
circuit, current is sent through the combination that hap¬ 
pens to be effective at that moment, and the drum is 
then given a one-step turn to the next combination as the 
signal stops. The next signal sent through repeats the 
same performance, but with the combination then effec¬ 
tive being used. 

Now the combinations can be arranged to do all kinds 
of different things. Supposing we are dealing with a 
model submarine, controlled by radio. The first combina¬ 
tion on the drum starts the motors; the second steers the 
craft to the left; the third brings the rudder to the nor¬ 
mal position; the fourth steers to the right; the fifth 
causes the driving motors to drop to half speed; the sixth 
deflects the diving rudders so that the craft submerges; 
the seventh brings the craft back to the surface again; the 
eighth stops the motors. 

But supposing we want the craft to steer to the right, 
when the combination then effective is the seventh, or 
the one that brings it back to the surface, what then? 
Simple enough. We simply send out one short snappy 
signal after another without appreciable pause between 
them, so that the craft does not have time to respond to 
any one of the controls, brought into play in rapid suc¬ 
cession until we reach the desired control, when we stop 
and the craft obeys. Generally, some indication is pro¬ 
vided so as to show just what combination happens to 
be operative at any given moment. Little colored lights 
can be used to indicate when the start of a cycle of com¬ 
binations is at hand, and the operator knows just how 



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many signals to send in order to reach the desired control. 

Another method is to use a steadily revolving drum 
aboard the vehicle or boat to be controlled. A watch, 
carefully synchronized so that its large hand will turn at 
the same speed as the revolving drum, is used by the 
operator. In this manner the operator, while watching his 
synchronized indicator, knows just the right moment to 
press the key in order to take advantage of any desired 
conditions for any desired command. 

The Radio Compass and What It Means 

Something has been said regarding the use of loops 
for receiving purposes. A loop consists of a wooden 
frame with a number of turns of wire. The loop is 
used in the same manner as would the secondary of a 
coupler in a receiving circuit, with a variable condenser 
or variometer to vary its wave length. No ground is 
employed. The loop receives signals loudest when it is 
pointing end on towards the transmitting station, and this 
fact has brought the radio' compass into existence. 

The radio compass is nothing more than a loop receiv¬ 
ing set. Thus the loop, which is mounted in such a 
manner as to be readily swung about on its vertical axis, 
is orientated until signals are picked up and a line can 
then be drawn on a corresponding map to indicate the 
direction from which the signals are coming. However, 
the loop indicates only the general line along which the 
signals are being received, and there is no telling whether 
they come from one end of the loop or the other. How¬ 
ever, in most instances the operator knows whether it is 
in one direction or the other, and he only requires the 
directive line. 

The radio compass generally consists of two or more 
radio compass stations, on shore, at the entrance to a 
harbor or some other point. A ship, wishing to know 
its exact bearings, calls up the radio compass stations, 
and these stations, by orientating their loops, secure two 
directive lines for the ship. Since the radio compass sta¬ 
tions are located a certain distance apart, forming the 


RADIO FOR EVERYBODY 


253 


base of an imaginary triangle, and since a pair of stations 
obtain an angle reading formed by the direction of the 
received signals and 'the base line, it is a simple matter 
with a known base line and two angles to construct an 



The radio compass which is employed as an aid in navigation. A 
number of turns of wire are wound about the large wooden frame 
which is rotatably mounted in the stationary frame, so that it can 

be orientated. 
























254 


RADIO FOR EVERYBODY 


imaginary triangle, the apex of which is the location of the 
ship. The radio compass stations then call up the ship 
and give the navigator his exact position. 

During the war the radio compass was employed for 
locating enemy radio transmitters. The Germans em¬ 
ployed the radio compass to guide their Zeppelins through 
the blackness of the night in their raids on London and 
Paris. That is why the Zeppelin flew with such rare 
precision over enemy territory and sea, and back to their 
flying fields. 

More recent developments in the radio compass have 
brought about a simpler method. Now the loop is carried 
on the ship, and the operator obtains directional readings 
from two shore stations whose locations are known, so 
that with a given apex angle and a known base line, it 
becomes possible to reconstruct an imaginary triangle and 
to determine the exact position of the ship. 

Wired Wireless 

For some time back it lias been possible simultaneously 
to transmit several telegraph messages over a single tele¬ 
graph circuit. Also, certain attempts have been made to 
develop a system of tuned or syntonic multiplex tele¬ 
graphy. But it has remained for the man who is at 
present Chief Signal Officer of the United States Army, 
Major General Squier, to develop a system of communi¬ 
cation known as wired wireless, which makes it possible to 
carry on as many as ten or more two-way simultaneous 
telephone conversations over one electrical circuit. It 
was in 1910 that Major General Squier (then Major), 
by a bold and ingenious adaptation of the fundamental 
principles and apparatus previously employed in radio 
telegraphy and telephony, developed the multiplex sys¬ 
tem which bears his name, and therefore established a 
distinct branch of the art of communication. 

The fundamental principle of the Squier system is the 
application of high frequency electrical resonance, or tun¬ 
ing as it is understood in radio work, to wire communi- 



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256 


RADIO FOR EVERYBODY 


cations. Previous attempts to solve the multiplex prob¬ 
lem had been based largely on electro-mechanical reson¬ 
ance. The system employs the elements of the radio 
telephone installation, the essential difference being that in 
place of the connections to earth and the usual antenna, 
we have, in this case, connections to the two wires con¬ 
stituting a physical pair. The two fundamental factors, 
then, in the Squier system of multiplex, are the utilization 
of electrical resonance and the use of a receiving device 
which delivers to the telephone receiver a varying undirec- 
tional current corresponding to the voice current supplied 
to the modulating device at the transmitting station. 
Whether the frequency of the carrier current is low or 
high does not modify the basic principles involved. In 
this system electro-magnetic waves of predetermined 
length are guided by the metallic circuit, instead of radiat¬ 
ing in all directions from an antenna. While there un¬ 
doubtedly is a certain amount of radiation from the phy¬ 
sical line, the over-all efficiency of the guided-wave sys¬ 
tem, as wired wireless is also called, is obviously materially 
higher than in the case of a free-wave system. This has 
been thoroughly confirmed by experience. 

It is reported that in general, guided-wave transmis¬ 
sion gives a more nearly perfect reproduction of the voice 
than does wire telephony. In ordinary telephony there 
are three inherent causes of distortion, to wit: the micro¬ 
phone, the telephone receiver, and that due to the line. 
The first two are, of course, present in the high fre¬ 
quency system. The distortion due to the line is, how¬ 
ever, absent. 

Another important aspect of communication is secrecy. 
When used as a direct private line of telephonic com¬ 
munication, as in the case of leased lines between busi¬ 
ness houses in different cities or for press work, we 
have in this method a system of communication which ac¬ 
cords a high degree of secrecy. Common experience in¬ 
dicates how little real privacy obtains when employing the 
ordinary telephone. While radio telephone has a distinct 


commercial radio telegraph station aerial located in New York and employed for maintaining com 
munication with ships. The steel towers and steel cross-arms serve to support the aerial wires. 
















258 


RADIO FOR EVERYBODY 


and very important field in communication at sea, it ob¬ 
viously has serious limitations when employed for strictly 
personal and business purposes. While there is no known 
means of communication which cannot be tapped, yet 
from the nature of the system direct guided-wave tele¬ 
phony possesses the greatest element of secrecy of any 
■telephonic means of communication, according to Chas. 
A. Culver, Ph.D., to whom the author is indebted for 
these facts on wired wireless. 

Another advantage of the guided-wave system is that 
communication may be maintained between two points 
when the physical circuit which serves as a guide for the 
high frequency waves is out of commission for ordinary 
telephone service. Both wires of the physical pair may 
be cut, the line short-circuited, and at least one of the 
wires grounded without interrupting communication over 
the super-channel. This has been repeatedly demonstrated 
and naturally means much in emergency service of all 
kinds. 

Another feature to be noted in connection with guided- 
wave telephony is the flexibility of the system. When 
used as a through trunk channel, a given set of equip¬ 
ment may, as previously indicated, be instantly shifted 
from one physical circuit to another. Further, the en¬ 
tire guided-wave equipment may be quickly transported 
from one point on a physical system to another, thus 
making it possible readily to increase the traffic-carrying 
capacity of the lines between points where a temporary 
congestion exists, due to seasonal or other causes. 

Guided wireless is but another achievement of modern 
radio—but another instance of how radio has collaborated 
rather than fought the wire telephone and telegraph, as 
was expected of it in the early days of the art. 


Chapter X. 


RADIO IN WORKING CLOTHES, OR 
THE APPLICATION OF RADIO TO 
EVERYDAY BUSINESS 


I F radio has a legitimate place in the home in the way 
of amusement and education, it has an even greater 
place in everyday business, especially that kind of busi¬ 
ness which extends out beyond the narrow confines of 
our immediate city and State and country and even con¬ 
tinent. Radio is a logical method of long-distance com¬ 
munication. It is alone in the ship-to-ship communication 
field, and it takes its place beside the telegraph and cable 
systems in our present scheme of things. 

Little need be said about the marine end of radio. 
Suffice it to remind ourselves that virtually every ship 
that carries passengers and any freighter of consequence 
are equipped with radio. No greater factor was ever in¬ 
troduced in maritime circles than radio, for ships are no 
longer out of touch with the world for days at a time. 
With the highly efficient ship installations as well as the 
powerful land stations, a ship is rarely isolated. 

Radio World-Wide Chains in the Making 

While radio may be used for short distances in place 
of telegraph lines, its real forte lies rather in long-distance 
work, side by side with the usual cables. It has been 
employed for inter-city work with some degree of suc¬ 
cess; but if all inter-city communication were conducted 


MO 


RADIO FOR EVERYBODY 


by radio instead of by the usual telegraph system it is 
obvious that the problem of interference would assume 
gigantic and finally prohibitive proportions. 

All the leading nations have fully realized the value 



Germany’s scheme of 1913 for world communication. A study 
of this network indicates that it is clearly influenced to a 
great extent by military as well as commercial considerations. 

The World War caused the permanent abandonment of this 

scheme. 

of radio as a means of long-distance communication. The 
recent war taught all nations that cables and telegraph 
lines can be severed, but the radio system cannot be 
interrupted. The nation with powerful radio stations is 
always assured of communication with the outside world. 

A number of world schemes of radio communication 
have been proposed in the past, and some of them are 
in the process of present realization. The earliest one 
is shown in the accompanying map. For this and the 
other maps shown in the following pages, as well as for 
much of the data on this phase of radio, the author is 
indebted to Alfred N. Goldsmith, Director, Research De¬ 
partment, Radio Corporation of America, and to the 
Journal of the American Institute of Electrical Engin- 
eers, in which Mr. Goldsmith’s data appeared. The ac¬ 
companying map, in which the distances are given in 
kilometers (a kilometer is roughly 3/5 of a mile) repre- 









RADIO FOR EVERYBODY 


261 


sents the extremely ambitious German scheme of 1913 
and is clearly influenced to a great extent by military as 
well as commercial considerations. The length of some 
of the jumps from station to station, taking into consider¬ 
ation the transmitting powers and the types of receiving 
apparatus then available, indicate that only partial or oc¬ 
casional service over the longer spans could have been 
expected, and then only at low speeds. It also appears 
that each, station was to handle several channels and 
therefore presumably to divide its time between its vari¬ 
ous correspondent stations. This type of service is more 
suited to press and propaganda work and light traffic 
than it is to the more exacting high-speed commercial 
requirements. This plan was not carried far before the 
war brought about its complete destruction. 

Our next map represents the first British Imperial 
schemes for radio communication, the so-called “All-Red 
Chain.” It dates from 1913, and was the plan of the 
British Marconi Company which submitted it to the 
British Government for approval. It was adopted, and 
some work was done along the lines indicated when the 
war intervened. The changes caused by the war and 



The British Imperial communication scheme of 1913, the so- 
called “All-Red Chain.” This scheme was adopted and some 
work was done along the lines indicated when the war inter¬ 
vened. The distances were too great, however, and the scheme 

was abandoned. 







262 


RADIO FOR EVERYBODY 


other causes led to its discontinuance and to rather seri¬ 
ous differences between the British Government and the 
Marconi Company. Afterwards the claims of the Marconi 
'Company were in part allowed and suitable financial com- 



Brititsh Imperial scheme of 1919 for radio communication. 
This is a less ambitious but more practical scheme than that 
of 1913. London is connected with distant points by means 
of short spans and relays, so that the distances are entirely 

feasible. 

pensation paid by the British Government for the loss of 
the original contractual profits. The plan itself included 
two routes from England to Australia with only two re¬ 
lays. It was a scheme involving large spans. London 
was the main center from which most of the communica¬ 
tion to distant points radiated directly. 

In 1919 and 1920 a British Government Committee re¬ 
considered the entire project of the Imperial radio scheme 
and recommended the less ambitious scheme shown in our 
next map. Here the Western Hemisphere is apparently 
neglected. London is not connected directly (without 
relays) to the more distant points, the average span is 
shorter, and the terminal points chosen are indicated ap¬ 
parently only in part by commercial considerations. This 
system will be Government-owned and operated, which 
may account for the nature of this plan, which is now 
being carried out. Only a very small portion of this 
plan has been carried out thus far. 








RADIO FOR EVERYBODY 


263 


Another very ambitious plan is due to France and is 
given in the accompanying map. It, too, is not planned 
entirely along commercial lines. Furthermore, it is clear 
that the French stations are intended to divide their time 
between a number of terminal stations and that ex¬ 
tremely long spans are planned. Of the stations shown 
on the French plan, several are built and several more 
are in process of construction. A considerable portion 
of this plan will, however, still have to be worked out in 
the future. It is noticeable that both the present French 
plan and the original German plan lay more stress on 
South American traffic than does the present British Im¬ 
perial scheme. 

Our Scheme for World-Wide Radio 
Then we come to our own pet scheme for world-wide 
radio—America’s plan. It differs in several important 
respects from the preceding plans. In the first place, 
every station shown thereon is either in operation or under 
construction, and by far the greater portion of the stations 
are those already in operation. Furthermore, for the sake 
of clearness, the large contemplated expansions of this 
plan are not shown on the map, although they will add 



ever, work is progressing on several large stations for this 

world-wide scheme. 









264 


RADIO FOR EVERYBODY 


nearly as many more channels of communication to the 
system as those already shown. In the second place, the 
plan shown is preeminently a commercial one, both in the 
placing of the terminal stations and in the practically 
exclusive use of each American station for a single 
channel. This latter feature permits the speedy handling 
of large volumes of traffic and avoids the troublesome 
delays which result when the time of a transmitting sta¬ 
tion is excessively “chopped up” or divided between too 
many receiving stations. The system is one of moderate 
and long spans, this being dictated to some extent by the 



Our American scheme for world-wide radio communication. 
Every station shown in this map is either in operation or 
under construction, and by far the greater portion of the 
stations are those already in operation. 

geographical location of the United States, its particular 
communication needs, and the absence of American po- 
sessions at certain points. The needs of the United States, 
considering these circumstances, have very greatly stimu¬ 
lated to the technical improvement of radio communication, 
and have led to the satisfactory solutions of the problems 
of long-distance communication. The case is an inter¬ 
esting illustration of the stimulating and helpful influence 
of natural obstacles. 

It has long been known that traffic from one country to 
another is by no means evenly distributed throughout 

























RADIO FOR EVERYBODY 


266 

the twenty-four hours of the day, the days of the week, or 
the months of the year. There are very pronounced peaks, 
and depressions or lull of traffic found to exist. Thus, 
the traffic between two countries will generally be heaviest 
for the hours during which daylight is common to both, 
and will drop to a minimum during the week end. It 
would be desirable to handle the peak of the load without 
permitting traffic to pile up, but this may not always be 
feasible for reasons of economy, both of equipment and 
of necessary personnel. This has led to the attempt to 
secure a high load factor for communication circuits by 
encouraging some of the users of the service to accept a 
certain delay in the delivery of their messages which are 
then sent at a reduced rate. Thus we find in addition to 
normal messages, which are sent in the order in which 
they are received, the “deferred” messages which are 
sent at the earliest opportunity when traffic has slackened 
sufficiently to permit their introduction. “Night letters” 
and “week end letters” ar$ sent during the periods in¬ 
dicated, and are obviously intended to fill an otherwise dull 
period in the circuit. On some circuits, “urgent” mes¬ 
sages are accepted which take priority over all others, and 
require the payment of a considerably increased rate. As 
a general rule, the minimum number of classes of mes¬ 
sages required to maintain an acceptable load factor is 
desirable not only because of the increased routine in 
handling traffic of many different classes but also because 
of the confusion in the public mind and the possible dis¬ 
satisfaction which results when the type of service rendered 
in any given case is not clearly understood in advance. 

The huge radio stations for inter-continental work are 
interesting studies. One of these stations is the Radio 
Central, located at Rocky Point, Long Island, some 70 
miles east of New York City. However, the actual opera¬ 
tion of this station takes place from New York City, the 
dots and dashes being formed by an operator in New 
York City and sent over telegraph lines to the Radio 
Central station, where they are automatically transferred 



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268 


RADIO FOR EVERYBODY 


to the powerful radio transmitter, consisting of a num¬ 
ber of 200-kilowatt high-frequency generators. Radio 
Central is in realty several stations in one. It comprises 
a number of separate transmitters so as to ensure simul¬ 
taneous communication with a number of stations abroad. 

Operating a Trans-Atlantic Station at a Distance 

It has always been a problem to control several hun¬ 
dred kilowatts of power at frequencies of 20,000 cycles per 
second by breaking it up into the dots and dashes of the 
telegraph code at speeds as high as 100 words per minute 
or more. When it is considered that this is equivalent 
to starting and stopping the flow of power fifty times 
per second, accurately and faultlessly, and that the initial 
control power is merely the few watts that can be drawn 
from the terminals of a telegraph line, the magnitude of 
the problem becomes evident. By the development of 
high-speed power relays and the new “magnetic amplifier/’ 
the problem has been very elegantly solved. The mag¬ 
netic amplifiers at the Rocky Point station enable the 
powerful transmitters to be operated at long distance, so 
to speak. These ferromagnetic devices accurately modu¬ 
late or control the flow of power from the alternators to 
the radiating system or aerial wires. 

To radiate the large amounts of power required to 
bridge transoceanic stretches, a large and lofty radiating 
system or aerial is required. The main tower at Tucker- 
ton (N. J.) is 850 feet high. At the New Brunswick (N. 
J.) station a row of 400-foot masts stretching 6,000 feet 
from the station support the “multiple tuned” aerial sys¬ 
tem. The latest form of aerial is that employed at the 
Radio Central station. It consists of a line of 410-foot 
towers with 150-foot spreaders at the top of each, and 
stretching a mile and a half from the station building. 
Twelve such rows of towers, each fed by its own high- 
frequency alternators and constituting in effect a separate 
transmitting station, will enable the Radio Central sta¬ 
tion to be used for simultaneous communication with an 



Twelve of the seventy-two steel towers comprising the aerial supports 
of the Radio Central wireless station. Each tower is 410 feet high 
while the cross-arm measures 150 feet from tip to tip 

























270 


RADIO FOR EVERYBODY 


equal number of receiving stations abroad when com¬ 
pletely realized. An area of about ten square miles is 
being devoted to this giant station, which will be by far 
the largest in the world when completed. 

In radio reception there have also been very marked 
advances during the last few years. Each row of appara¬ 
tus in its especially shielded cases is capable of handling 
one transoceanic channel. Each operator is provided with 
a telegraph key controlling the transmitter on the corre¬ 
sponding circuit, so that he can, if necessary, “break’’ 
or interrupt the transmitting operator to obtain a correc¬ 
tion or other information from the station which he is 
receiving. 

When reception at high speed was desired, recording 
was sometimes accomplished on modified phonographs 
which were run rapidly and the records were later tran¬ 
scribed at lower speeds by a number of operators. This 
method of receiving at high speed has been superseded by 
modern forms of ink recorders especially developed for 
radio reception. Photographic recorders, in which the 
received signals are photographed as a wavy line on a 
paper ribbon, have also been used in high speed reception. 

Wire and radio communication, according to Mr. Gold¬ 
smith, should work hand in hand in any comprehensive 
scheme of world communication. The land wires and 
cables have very clearly demonstrated their great capabili¬ 
ties and usefulness; but radio communication, even at this 
early state in its development, has shown that it should 
be considered as an integral element of any well-considered 
plan for communicating all over the globe. Today ap¬ 
proximately 15 per cent of the traffic across the Atlantic 
from the United States is handled via radio, which is a 
hopeful showing for a new art, to be sure. To the extent 
that there is harmonious and intelligent co-operation be¬ 
tween the various communication systems, we may hope 
for the satisfactory solution of the problem of giving every 
person on earth rapid and reliable communication. 


RADIO FOR EVERYBODY 


271 


When Wire and Wireless Work Together 

Fortunately, there are no physical limitations to prevent 
the interconnection by skilled persons of wire line and 
radio circuits. Messages received by radio telegraphy or 
radio telephony can be automatically transferred to wire 
lines and over them relayed to any point reached by them. 
Conversely, telegraph or telephone signals on a wire line 
can be used to control radio telegraph or radio telephone 
transmitters. So that any wire system may be extended 
by the addition of radio relays and, reciprocally, any 
radio system may be extended by the addition of wire 
relays. This process of adding wire and radio links or 
relays to each other can be carried on to practically any 
desired extent and should constitute an element in the 
communication systems of the future. On a moderate 
scale it is being carried out commercially today in the 
case of messages from European countries received by 
the Radio Corporation of America at its receiving stations 
on Long Island and in New Jersey. From these points 
the messages are automatically relayed over wire lines 
to the New York traffic office of the company in the heart 
of the financial district, where the receiving operators 
take down the messages by ear, if sent at hand speed, or 
the messages are automatically written down by ink re¬ 
corders if received at high speed. 

A similar transfer of telephone signals to and from 
wire lines has been demonstrated as a commercial propo 
sition in highly successful fashion by the American Tele¬ 
phone & Telegraph Company, in the Avalon-Los Angeles 
radio toll circuit, in which regular radio telephone mes¬ 
sages are sent by radio over a 31 y 2 air gap without the 
subscribers realizing that their conversation is being 
handled in any other manner than by wires. Experiments 
have been carried on with the steamship Gloucester and 
the Deal Beach radio-phone experimental station, and per¬ 
sons have talked over the regular telephone instrument 
in their home to the ship at sea. More recently, still 
more spectacular experiments have been carried on with 


272 


RADIO FOR EVERYBODY 


the steamship “America” while 400 miles out at sea. 
It is only a matter of time when we shall be able to 
’phone to the ship at sea with the same ease that we 
call up long-distance points. 

Certain countries, such as the United States, are so 
situated geographically as to serve naturally as important 
relay centers for inter-continental communications. Com¬ 
munications from Europe to South America, and from 
Europe to the Far East naturally pass over the United 
States. In view of the rapid rate at which the power, 
required to bridge a certain distance reliably by radio, 
increases with distance for spans of more than a few 
thousand miles, it is advantageous, holds Mr. Goldsmith, 
to establish relay points in the United States whereby 
communications from Europe to the regions named will 
be received in the United States and thence automatically 
or otherwise relayed to their destinations. 

The Traffic Capacity of the Long-Distance Ether 

Some doubt may have been entertained by engineers as 
to the traffic-carrying capacity of the ether for long-dis¬ 
tance communication. The figures for long-distance tele¬ 
graphy can be at least roughly estimated without serious 
difficulty. We shall assume continuous wave transmis¬ 
sion, with an appropriate form of key modulation in 
sending the dots and dashes, and without any tone modula¬ 
tion whatever. Under these conditions, and taking into 
account both side bands produced as the result of actual 
transmission, it has been found that a speed of 100 words 
(or 500 letters) per minute corresponds to the occupa¬ 
tion of a band of frequencies in the ether roughly 100 
cycles wide. This is on the basis that the radio-fre¬ 
quency generator maintains its frequency constant during 
transmission. We shall also assume that the receiver is 
sufficiently selective to exclude all signals on frequencies 
outside of this 100 cycle band. Under these conditions, 
we may say roughly that on each cycle per second of 
available ether frequencies we can transmit one word 


RADIO FOR EVERYBODY 


273 


per minute. Assuming further that long-distance traffic 
will be handled in the range of wave lengths between 
6,000 meters and 40,000 meters, a reasonable assump¬ 
tion on the basis of present-day practice—and also a 
conservative one—we shall have available a band of ether 
frequencies of from 50,000 to 7,500 cycles per second, 
or 42,500 cycles in all. According, we can ultimately 
transmit at least 42,500 words per minute via radio over 
long distances, or no less than 61,200,000 words per day. 
If we extend the range of available wave lengths for long¬ 
distance communication below 6,000 meters through the 
further reduction of atmospheric disturbances; if we 
eliminate one of the side bands resulting from transmis¬ 
sion; and if we assume the possibility of using the same 
wave length for transmission at several points of the 
earth’s surface with directional discrimination between 
several transmitters at the receiving station, the already 
enormous daily message-carrying capacity of the ether 
will be greatly increased. As a matter of comparison, 
we may state that the figure of 61,200,000 words per 
day is roughly 150 times the actual traffic sent across the 
Atlantic Ocean by cable and radio at the present time. 

A number of perfectly reasonable requirements must be 
met by transmitting and receiving stations in order to 
realize the ultimate capacity mentioned above, according 
to Mr. Goldsmith. The transmitters must have strictly 
constant generator frequency consistent with their key 
signaling speed and the receivers must be highly selective 
for a correspondingly narrow range of frequencies and 
yet follow the signals accurately. Even today radio en¬ 
gineers are confident that these results will shortly be 
obtained by carefully chosen technical expedients. 

The nature of world communication makes it interna¬ 
tional in character. Both wire lines and radio waves know 
nothing of national boundaries, a fact which is sometimes 
resented by the nations, particularly during hostilities. 
It is this essentially international character of long-dis¬ 
tance communications, particularly of the unguided 


274 


RADIO FOR EVERYBODY 


variety, which has led to the international regulation of 
radio communication. In 1912, the London Radio Con¬ 
vention was agreed to by most of the nations of the 
world and given force by corresponding national legisla¬ 
tion in each case. These regulations of the London Con¬ 
vention were fairly general in character and covered the 
most essential points only. Thus there was left con¬ 
siderable and proper leeway for each nation to settle its 
own national problems in communication according to 
local needs and the nature of local institutions. It would 
seem that some such policy is wise, especially where im¬ 
portant matters of truly international scope clearly require 
settlement in the interests of effecive communication and 
to avoid inevitable disputes. Beyond this point which is 
defined without much difficulty by the experts in the art, 
regulation becomes burdensome and tends to retard the 
progress of the radio art and to discourage initiative. 

For the rapid growth of world communication, as far 
as a radio is concerned the degree of regulation of the art 
by the various governments should be restricted to the 
enforcement of the international regulations together 
with such control of the nationality of the owners and 
personnel of the radio companies as may be deemed nec¬ 
essary for national security. The entire field of un¬ 
guided communication, as Mr. Goldsmith calls radio, is 
so new and is developing so rapidly that great harm can 
be done by well-meaning but injudicious legislators and 
officials. Like all pioneer arts, its successful and speedy 
development depends on wide freedom of experiment by 
enterprising investigators and encouragement of effort on 
the part of wide-awake companies. 


Chapter XI. 


HOW TO CONSTRUCT SIMPLE RADIO 
RECEIVING SETS FOR RADIO¬ 
PHONE PROGRAMS 



ND now for those who wish to construct their own 


^ V. simple receiving outfits, here is a chapter devoted 
to their particular interests. 

First of all we shall describe an entire receiving station, 
including antenna as well as a crystal detector receiving 
set. This station will enable one to hear the messages sent 
from medium^power transmitting stations within an area 
about the size of a large city, and to hear high-power 
stations within 50 miles, provided the waves used by those 
stations have wave frequencies between 500 and 1500 
kilocycles per second, which, translated into plain English, 
means wave lengths between 600 and 200 meters. Much 
greater distances are often covered, especially at night. 
If a person constructs the coil and other parts as indicated, 
the total cost of this set can be kept down to about $6.00. 
If, however, a specially efficient outfit is desired, the cost 
may be about $15.00. 

The Essential Parts of Receiving Station 

The set about to be described has been designed by the 
Bureau of Standards at the request of the States Relations 
Service of the United States Department of Agriculture, 
for the use of boys and girls radio clubs. 

There are five essential parts to this receiving station, 


276 


RADIO FOR EVERYBODY 


as well as any other receiving station, namely: the antenna, 
lightning switch, ground connections, receiving set proper, 
and telephone receivers. The received signals come into 
the receiving set through the antenna and ground connec¬ 
tion. In the receiving set they are converted into an 
electric current which produces the sounds in the telephone 
receivers. The telephone receiver is either one or a pair 
of telephone receivers worn on the head of the listener. 
A number of telephones may be used with such a set, 
but a loud-speaking device, which does away with head 
phones, is not practical with a simple set of this kind. 

The purpose of the lightning switch is to protect the 
receiving set from damage by lightning. It is used to 
connect the antenna directly to ground when the receiving 
station is not being used. When the antenna and the 
connection to the ground are properly made and the light¬ 
ning switch is closed, an antenna acts as a lightning rod 
and is a protection rather than a source of danger to the 
building. 

o \ 

The principal part of the station is the receiving set 
proper. In the set described in the following paragraphs 
it is subdivided into two parts, the tuner and the detector, 
and in more complicated sets still other elements are added. 

The Antenna, Lightning Switch and Ground 

Connections 

The antenna is simply a wire suspended between two 
elevated points. Wherever there are two buildings, or a 
house and a tree, or two trees with one of them very close 
to the house, it relieves one of the need of erecting one or 
both antenna supports. The antenna should not be less 
than 30 feet above the ground and its length should be 
about 75 feet. (See Eig. 1.) While this figure indicates 
a horizontal antenna, it is not important that it be strictly 
horizontal. It is in fact desirable to have the far end as 
high as possible. The “lead-in” wire or drop-wire from 
the antenna itself should run as directly as possible to the 
lightning switch. If the position of the adjoining build¬ 
ings or trees is such that the distance between them is 


RADIO FOR EVERYBODY 


277 


greater than about 85 feet, the antenna can still be held 
to a 75 foot distance between the insulators by increasing 
the length of the piece of rope (D) to which the far end 
of the antenna is attached. The rope (H) tieing the 
antenna insulator to the house should not be lengthened 
to overcome this difficulty, because by so doing the antenna 
“lead-in” or drop wire (J) would be lengthened. 

Details of Parts —The parts will be mentioned here by 
reference to the letters appearing in Figures 1 and 2. 



Fig. 1.—Construction of antenna for reception purposes. A— 
screw eye; B—rope; C—pulley; D—rope; E insulator; F 
antenna; G—Insulator; H—rope; I—screw eye; J —lead-in wire; 

K—lightning switch; L—ground wire; M—ground pipe; N— 
lead to receiving set; O—insulating tube. 

A and I are screw eyes sufficiently strong to anchor the 
antenna at the ends. 

B and H are pieces of rope or ^ inch in diameter, 
just long enough to allow the antenna to swing clear of 
the two supports. 

D is a piece of 3/s or ^ inch rope sufficiently long to 
make the distance between E and G about 75 feet. 

C is a single block pulley which may be used if readily 

available. 






























278 


RADIO FOR EVERYBODY 


E and G are two insulators which may be constructed 
of any dry hardwood of sufficient strength to withstand 
the strain of the antenna; blocks about V /2 x 2 x 10 inches 
will serve. The holes should be drilled as shown in Fig. 1 
sufficiently far from the ends to give proper strength. If 
wood is used the insulators should be boiled in paraffin 
for about one hour. If porcelain wiring cleats are avail¬ 
able they may be substituted instead of the wood insulators. 
If any unglazed porcelain is used as insulators, it should 
be boiled in paraffin the same as the wood. Regular 
antenna insulators are advertised on the market, but the 
two improvised types just mentioned will be satisfactory 
for an amateur receiving antenna. 

F is the antenna about 75 feet between the insulators 
E and G. The wire may be No. 14 or 16 copper wire 
either bare or insulated. The end of the antenna farthest 
from the receiving set may be secured to the insulator 
(E) by any satisfactory method, being careful not to kink 
the wire. Draw the other end of the antenna wire through 
the other insulator (G) to a point where the two insulators 
are separated by about 75 feet, twist the insulator (G) 
so as to form an anchor as shown in Fig. 1. The re¬ 
mainder of the antenna wire (J) which now constitutes 
the “lead-in” or drop-wire should be just long enough 
to reach the lightning switch. 

K is the lightning switch. For the purpose of a small 
antenna this switch may be the ordinary porcelain base, 
30 ampere, single-pole double-throw battery switch. These 
switches as ordinarily available have a porcelain base about 
1 by 4 inches. The “lead-in” wire (J) is attached to this 
switch at the middle point. The switch blade should 
always be thrown to the lower clip when the receiving 
set is not actually being used and to the upper clip when 
it is desired to receive signals. 

L is the ground wire for the lightning switch; it may 
be a piece of the same size wire as used in the antenna, 
of sufficient length to reach from the lower clip of the 
lightning switch (K) to the clamp on the ground rod (M). 

M is a piece of iron pipe or rod driven 3 to 6 feet into 


RADIO FOR EVERYBODY 


279 


the ground, preferably where the ground is moist, and 
extending a sufficient distance above the ground in order 
that the ground clamp may be fastened to it. Scrape the 
rust or paint from the pipe before driving in the ground. 



N is a wire leading from the upper clip of the lightning 
switch through the porcelain tube (O) to the receiving 
set binding post marked “antenna.” 

O is a porcelain tube of sufficient length to reach 
through the window casing or wall. This tube should be 
mounted in the casing or wall so that it slopes down 






































































280 


RADIO FOR EVERYBODY 


toward the outside of the building. This is done to keep 
the rain from following the tube through the wall to the 
interior. 

Fig. 2 shows the radio receiving set installed in some 
part of the house. 

P is the receiving set which is described in detail below. 

N is the wire leading from the “antenna” binding post 
of the receiving set through the porcelain tube to the 
upper clip of the lightning switch. This wire, as well as 
the wire shown by Q, should be insulated and preferably 
flexible. A piece of ordinary lamp cord might be un¬ 
braided and serve for these two leads. 

Q is a piece of flexible wire leading from the receiving 
set binding post marked “ground” to a water pipe, heating 
system or some other metallic conductor to ground, except 
M, Fig. 1. If there are no water pipes nor radiators in 
the room in which the receiving set is located, the wire 
should be run out of doors and connected to a special 
“ground” below the window, which shall not be the same 
as the “ground” for the lightning switch. It is essential 
that for the best operation of the receiving set this 
“ground” be of the very best type. If the soil near the 
house is dry it is necessary to drive one or more pipes or 
rods sufficiently deep to encounter moist earth and connect 
the ground wire to the pipes or rods. This distance will 
ordinarily not exceed 6 feet. Where clay soil is encoun¬ 
tered this distance may be reduced to 3 feet, while in 
sandy soil it may be increased to 10 feet. If some other 
metallic conductor, such as the casing of a drilled well, is 
not far away from the window, it will be a satisfactory 
“ground.” 

Tuner, Detector and Telephone 

At least the telephone will have to be purchased. The 
tuner and certain accessories can be made at home. 

Timer ( R, Fig. 3)—This is a piece of cardboard or 
other non-metallic tubing with turns of copper wire wound 
around it. The cardboard tubing may be an oatmeal box. 
Its construction is described in detail below. 


RADIO FOR EVERYBODY 


281 


Crystal Detector (S, Fig. 3)—The construction of a 
crystal detector may be of very simple design and quite 
satisfactory. The crystal, as it is ordinarily purchased, 
may be unmounted or mounted in a little block of metal. 
For mechanical reasons the mounted type may be more 
satisfactory, but that is of no great consequence. It is 
very important, however, that a very good tested crystal 
be used. It is probable also that a galena crystal will be 
more satisfactory to the beginner. 

The crystal detector may be made up of a tested crystal, 
three wood screws, short pieces of copper wire, a nail, 
set screw type of binding post, and a wood knob or cork. 
The tested crystal is held in position on the wood base 
by three brass wood-screws as shown at I Fig. 3. A bare 
copper wire may be wrapped tightly around the three 
brass screws for contact. The assembling of the rest of 
the crystal detector is quite clearly shown in Fig. 3. 

Phone ( T, Fig. 3)—It is desirable to use a pair of 
telephone receivers connected by a head band, usually 
called a double telephone headset. The telephone receivers 
may be any of the standard commercial makes having a 
resistance of between 2000 and 3000 ohms. The double 
telephone receivers will cost more than all the other parts 
of the station combined but it is desirable to get them, 
especially if one plans to improve his receiving set later. 
If one does not care to invest in a set of double telephone 
receivers a single telephone receiver with a head band may 
be used; it gives results somewhat less satisfactory. 

Accessories —Under the heading of accessory equip¬ 
ment may be listed binding posts, switch arms, switch con¬ 
tacts, test-buzzer, dry battery and boards on which to 
mount the complete apparatus. The binding posts, switch 
arms and switch contacts may all be purchased from 
dealers who handle such goods or they may be quite readily 
improvised at home. There is nothing peculiar about the 
pieces of wood on which the equipment is mounted. They 
may be obtained from a dry packing-box and covered with 
paraffin to keep out moisture. 


282 


RADIO FOR EVERYBODY 


Details of Construction 

The following is a detailed description of the method 
of winding the coil, construction of the wood panels, and 
mounting and wiring the apparatus. 

Tuner —See R. Fig. 3. Having supplied one’s self with 
a piece of cardboard tubing 4 inches in diameter and 
about y 2 pound of No. 24 (or No. 26) double cotton cov¬ 
ered copper wire, one is ready to start the winding of the 
tuner. Punch two holes in the tube about y 2 inch from 
one end as shown at 2 on Fig. 3. Weave the wire through 
these holes in such a way that the end of the wire will be 
quite firmly anchored, leaving about 12 inches of the wire 
free for connections. Start with the remainder of the 
wire to wrap the several turns in a single layer about the 
tube, tightly and closely together. After ten complete 
turns have been wound on the tube hold those turns snugly 
while a tap is being taken off. This tap is made by making 
a 6 inch loop of the wire and twisting it together at such 
a place that it will be slightly staggered from the first tap. 
This method of taking off taps is shown quite clearly at 
U, Fig. 3. Proceed in this manner until six twisted taps 
have been taken off at every ten turns. After these first 
seventy turns have been wound on the tube then take off 
a 6 inch twisted tap for every succeeding single turn until 
ten additional turns have been wound on the tube. After 
winding the last turn of wire anchor the end by weaving 
it through two holes punched in the tube much as was 
done at the start, leaving about 12 inches of wire free for 
connecting. It is to be understood that each of the eighteen 
taps is slightly staggered from the one just above, so that 
the several taps will not be bunched along one line on the 
cardboard tube. See Fig. 3. It would be advisable, after 
winding the tuner as just described, to dip the tuner in hot 
paraffin. This will help to exclude moisture. 

Upright Panel and Base —Having completed the tuner 
to this point, set it aside and construct the upright panel 
shown in Fig. 4. This panel may be a piece of wood 
approximately y 2 inch thick. The position of the several 



Fig. 3.—Constructional details of the simple radio receiving 
set designed by the l'. S. Bureau of Standards for the use of 

laymen. 











































































































284 


RADIO FOR EVERYBODY 


holes for the 'binding posts, switch arms and switch con¬ 
tacts may first be laid out and drilled. The “antenna” 
and “ground” binding posts may be ordinary J /$ inch brass 
bolts of sufficient length and supplied with three nuts and 
two washers. The first nut binds the bolt to the panel, the 
second nut holds one of the short pieces of stifif wire, 
while the third nut holds the antenna or ground wire as 
the case may be. The switch arm with knob shown at V, 
Eig. 3, may be purchased in the assembled form or it may 
be constructed from a thin slice cut from a broom handle 
and a bolt of sufficient length equipped with four nuts 
and two washers together with a narrow strip of thin 
brass somewhat as shown. The switch contacts (W, 
Fig. 3) may be of the regular type furnished for this 
purpose or they may be brass bolts equipped with one nut 
and one washer each or they may even be nails driven 
through the panel with an individual tap fastened under 
the head or soldered to the projection of the nail through 
the panel. The switch contacts should be just close enough 
that the switch arm will not drop between the contacts but 
also far enough apart that the switch arm can be set so 
as to touch only one contact at a time. 

The telephone binding post should preferably be of the 
set screw type as shown as X, Fig. 3. 

Instructions for Wiring 

Braving constructed the several parts just mentioned 
and mounted them on the wood base, one is ready to con¬ 
nect the several taps to the switch contacts and attach the 
other necessary wires. Scrape the cotton insulation from 
the loop ends of the sixteen twisted taps as well as from 
the ends of the two single wire taps coming from the 
first and last turns. Fasten the bare ends of these wires 
to the proper switch contacts as shown by the correspond¬ 
ing numbers in Fig. 3. One should be careful not to cut 
or break any of the looped taps. It would be preferable 
to fasten the connecting wires to the switch contacts by 
binding them between the washer and the nut as shown at 
3, Fig. 3. A wire is run from the back of the binding 


RADIO FOR EVERYBODY 


285 


post marked “ground” (Fig. 3) to the back of the left- 
hand switch-arm bolt (Y), thence to underneath the left- 
hand binding post marked “phones.” A wire is then run 
from underneath the right-hand binding post market 
"phones” to underneath the binding post (4, Fig. 3). which 
forms a part of the crystal detector. A piece of No. 24 
bare copper wire about 2 l /> inches long, one end of which 
is twisted tightly around the nail (the nail passing through 



Assembled receiving set, ready for use. This little set will 
receive over distances of 25 to possibly 35 miles from radio¬ 
phone broadcasting stations. 


binding post 4) the other end of which rests gently by its 
own weight on the crystal (1). The bare copper wire 
which was wrapped tightly around the three brsss wood- 
screws holding the crystal in place is led to and fastened 
at the rear of the right-hand switch-arm bolt (V), thence 
to the upper left-hand binding post marked “antenna.” 
As much as possible of this wiring is shown in Fig. 3. 











286 


RADIO FOR EVERYBODY 


Directions for Operating 

After all the parts of this crystal-detector radio receiv¬ 
ing set have been constructed and assembled the first 
essential operation is to adjust the little piece of wire, 
which rests lightly on the crystal, to a sensitive point. 
This may be accomplished in several different ways; the 
use of a miniature buzzer transmitter is very satisfactory. 
Assuming that the most sensitive point on the crystal has 
been found by method described in paragraph below, “The 
Test Buzzer,” the rest of the operation is to get the radio 
receiving set in resonance or in tune with the station from 
which one wishes to hear messages. The tuning of the 
receiving set is attained by adjusting the inductance of the 
tuner. That is, one or both of the switch arms are rotated 
until the proper number of turns of wire of the tuner are 
made a part of the metallic circuit between the antenna 
and ground, so that together with the capacity of the 
antenna the receiving circuit is in resonance with the par¬ 
ticular transmitting station. It will be remembered that 
there are ten turns of wire between each of the first eight 
switch contacts and only one turn of wire between each 
two of the other contacts. The tuning of the receiving set 
is best accomplished by setting the right-hand switch arm 
on contact (1) and rotating the left-hand switch arm over 
all its contacts. If the desired signals are not heard, move 
the right-hand switch arm to contact (2) and again rotate 
the left-hand switch arm throughout its range. Proceed 
in this manner until the desired signals are head. 

It will be advantageous for the one using this radio 
receiving equipment to find out the wave frequencies 
'(wave length) used by the several radio transmitting sta¬ 
tions in his immediate vicinity. 

The Test Buzzer —(Z, Fig. 3)—As mentioned previ¬ 
ously, it is easy to find the more sensitive spots on the 
crystal by using a test buzzer. The test buzzer is used as 
a miniature local transmitting set. When connected to 
the receiving set as shown at Z, Fig. 3, the current pro¬ 
duced by the buzzer will be converted into sound by the 


RADIO FOR EVERYBODY 287 

telephone receivers and the crystal, the loudness of the 
sound depending on what part of the crystal is in contact 
with the fine wire. To find the most sensitive spot connect 
the test buzzer to the receiving set as directed, close the 
switch (5, Fig. 3) (and if necessary adjust the buzzer 
armature so that a clear note is emitted by the buzzer), set 
the right-hand switch arm on contact point No. 8, fasten 
the telephone receivers to the binding posts marked 
“phones,” loose the set screw of the binding post slightly 
and change the position of the fine wire (6, Fig. 3) to 
several positions of contact with the crystal until the 
loudest sound is heard in the phones, then tighten the 
binding post set screw (4) slightly. 

Approximate Cost of Parts 

The following list shows the approximate cost of the 
parts used in the construction of this radio receiving 
station. The total cost will depend largely on the kind 
of apparatus purchased and on the number of parts con¬ 


structed at home. 

Antenna— 

Wire—'Copper, bare or insulated, No. 14, 

100 to 150 feet, about. 0.75 

Rope—or inch.2 cents per foot 

2 insulators, porcelain. 0.20 

1 pulley. 0.15 

Lightning switch—30 ampere battery switch. 0.30 

1 porcelain tube. 0.10 

Ground Connections— 

Wire (same kind as antenna wire). 

1 clamp. 0.15 

1 iron pipe or rod. 0.25 

Receiving Set— 

p 2 pound No. 24 copper wire double cot¬ 
ton covered. 0.75 

1 cardboard box. 

2 switch knobs and blades complete. 1.00 

18 switch contacts and nuts. 0.75 

3 bindings posts—set screw type. 0.45 













288 


RADIO FOR EVERYBODY 


2 binding posts—any type. 0.30 

1 crystal—tested. 0.25 

3 wood screws, brass, Y inch long. 0.03 

Wood for panels (from packing box). 

2 pounds paraffin. 0.30 

Lamp cord.2 to 3 cents per foot 

Test buzzer. 0.50 

Dry battery. 0.30 

Telephone receivers. 4.00 to 8.00* 


Total.11.00 15.00 


*Still more efficient and expensive telephone receivers 
are available at prices ranging to about $20.00. 

If nothing but the antenna wire, lightning switch, por¬ 
celain tube, crystal, telephone receiver, bolts and buzzer 
are purchased this total can be reduced to about $6.00. 

A Simple Vacuum Receiving Set 

Using the same antenna, ground connection and light¬ 
ning switch as already described, the more ambitious radio 
enthusiast may readily construct a simple vacuum tube 
receiving set which will give better results than the crystal 
detector set although it is considerably more complicated. 

This set, which is shown completely assembled in the 
accompanying drawing, comprises a loose-coupler tuner, 
provided with primary and secondary switches, primary 
and secondary variable condenser, grid leak, vacuum tube, 
vacuum tube socket, filament rheostat, filament battery 
and high voltage or plate battery. If necessary, most of 
the material may be home made, with the exception of 
the vacuum tube, grid leak, vacuum tube socket, batteries, 
filament rheostat and telephone receivers. 

The first step is to construct the loose-coupler tuner. 
This consists of a primary and a secondary winding, each 
one being tapped off at every ten turns and the taps being 
brought to the switch points of the primary and secondary 
switches. The primary is a mailing tube measuring five 
or six inches in diameter, on which is wound 100 turns 
of No. 20, 22 or 24 B. & S. gauge double cotton or double 












Construction details of the loose-coupler tuner employed for the simple vacuum tube receiving set. This instrument 

may he made by anyone possessing ordinary household tools. 



IO POINT SWITi 















































290 


RADIO FOR EVERYBODY 


silk covered wire, with the adjacent turns side by side. 
At every ten turns the wire is looped and twisted together 
so as to form a tap, the loop being passed through a hole 
in the mailing tube and the tap brought over to its respec¬ 
tive switch point, to which it is connected after the primary 
is ready for assembling. The final turn of the primary 
is passed through two holes close together so as to hold 
the winding firmly in place, and the end brought to the 
last switch point. When the primary is completely wound, 
it is mounted on a block of wood which acts as the sup¬ 
port. It is left 'largely to the builder as to how the primary 
is mounted. One method is to use a round piece of wood 
of about the same diameter as the inside measurement 
of the mailing tube. This block is nailed on the end piece 
and the mailing tube is slipped over the block to which it 
can be firmly glued or tacked. The taps have, of course, 
been scraped and connected with their respective switch 
points. 

Now for the secondary. This is constructed in virtually 
the same manner, using a smaller mailing tube which fits 
inside the primary tube. The winding is of the same sized 
wire for the sake of simplicity, and taps are taken at every 
ten points and brought to their respective points of a ten- 
point switch. The mounting of the secondary must be 
carried out in the same manner as the primary, except 
that the latter has a stationary support, nailed firmly on 
the base board of the loose-coupler, while the former has 
a movable.support. The movable support is made up in 
the manner indicated in our drawing, so that the secondary 
can be moved in and out of the primary, between guides. 

This completes the loose-coupler. The next step is to 
construct variable condensers, which are necessary for 
fine tuning. Inasmuch as the loose-coupler tunes only in 
big steps of ten turns at a time, it is necessary to employ 
variable condensers in order to effect sharp tuning so 
essential in the satisfactory reception of radio-phone 
service. 

The simplest variable condenser to construct is probably 
the so-ca'lled book type, which is illustrated in our drawing. 


RADIO FOR EVERYBODY 


291 


This consists of two pieces of wood, which are fastened 
together by means of an ordinary hinge, so that they may 
be moved toward each other or drawn apart, as the case 
may be. A small wooden strip or even a nail prevents the 
two pieces from coming into actual contact. On each 
strip of wood is mounted a piece of sheet aluminum or 
copper, which acts as one of the condenser plates. Bind¬ 
ing posts are used in the manner indicated to make proper 


BINDING POST 



Top view of book type of variable condenser, consisting of 
two boards hinged together, two pieces of copper or aluminum 
sheeting, arranged as shown. 


connections. The capacity of such a condenser is in¬ 
creased by moving the plates close together and lessened 
by moving them farther apart. 

Items That Must Be Bought 

The grid leak consists of a very high resistance unit. 
This is obtained by drawing a pencil line on a sheet of 
paper, and clamping this pencil line between two heavy . 
copper washers so that the grid current for the vacuum 
tube must flow through this exceedingly high resistance. 
However, the grid leak has to be constructed with con- 


292 


RADIO FOR EVERYBODY 


siderable accuracy, so that it may be the part of better 
judgment to purchase a grid leak at any radio supply 
store. It is a matter of 50 or 75 cents, and it is certain to 
be correctly designed and constructed. 

The vacuum tube must be purchased, of course, and 
aside from the telephone receivers and batteries, it repre¬ 
sents the most expensive single item for such a set. The 
tube must be a detector tube, also known as a gassy tube, 
and costs either $4.00 or $5.00, depending on the type 
employed. A vacuum tube socket must also be purchased, 
at a cost of anywhere from 50 cents to $1.50, depending 
on the type selected. 

A vacuum tube requires two batteries, namely, the 
filament battery of six volts and the B or plate battery 
of 223/2 volts. A 6-volt storage battery gives the best 
service for filament current, because the heavy drain of 
the vacuum tube filament soon wears out any dry battery. 
Still, if the reader is going to construct his own set it is 
almost certain that he will not want to go to the expense 
of purchasing a storage battery, hence dry batteries must 
be used. Four or five cells of dry battery may be used, 
although it will increase the life of the dry cells a great 
deal if two sets are employed, connected in what is known 
as series-parallel. That is to say, four or five cells are 
connected in series, with the carbon of one coil going to 
the zinc of the next cell. Then, the zinc of one battery is 
connected with the zinc of the other battery, and the 
carbon of one battery with the carbon of the other battery. 
This arrangement gives a battery of twice the amperage 
or current, and the drain caused by the tube is not so 
serious. 

The filament rheostat may be made, although it will 
hardly pay when simple rheostats can be purchased for 
one dollar or less. The rheostat serves to control the 
filament current, which must be accurately regulated for 
satisfactory results, since the vacuum tube is a delicate 
piece of mechanism. 

The B or plate battery must be purchased. This battery 


RADIO FOR EVERYBODY 


293 


comes in a compact block, either in the large or the small 
size. There are two types of B battery, namely, the fixed 
voltage and the variable voltage types. The latter is rec¬ 
ommended, since it permits of regulating the plate voltage 
applied to the vacuum tube, and this is a most important 
consideration with many vacuum tubes. 

The telephone receivers must be bought, and it is well 
to invest in good receivers. If there is anything that 
tends to make or undo a radio receiving set it is the tele¬ 
phone receivers. Inexpensive receivers are certain to 
prove the most expensive in the long run, because the 



Arrangement of dry cells in series-parallel, in order to 
obtain a steadier voltage and a longer life from the dry 
battery used with vacuum tubes. 


owner of such receivers may soon tire of them and ask 
for something better, only to find that his inexpensive 
receivers have no market value and must therefore be 
junked. 

With all the various components constructed and pur¬ 
chased, ready for use, they are assembled as shown in our 
assembly drawing. To operate the set, the primary switch 
is placed on the middle switch point and the variable con¬ 
denser in the aerial-ground or primary circuit is varied 
slowly. Meanwhile, the secondary switch is also placed 
on the middle switch point, and the secondary condenser 
is also varied. When the desired signal or radio-phone 



294 


RADIO FOR EVERYBODY 


service is intercepted, the switches and variable condensers 
are rapidly adjusted until the best results are obtained. 
All the while, of course, the vacuum tube is lighted and 
the filament rheostat is carefully adjusted for the loudest 
yet clearest sounds. 

Such a set will work satisfactorily over a range of 50 
miles, although it is not as satisfactory as one using the 
Armstrong regenerative or feed-back circuit, which is 
somewhat more involved and is described further on in 
simple form for home construction purposes. However, 
the various radio supply houses are now offering the 
various components for regenerative receiving sets, as well 
as amplifier units. An excellent receiving set may be 
constructed by purchasing a vario-coupler, two vario¬ 
meters, grid leak and grid condenser, and the various 
other accessories such as the rheostat, vacuum tube and 
socket, binding posts, and so on, connected as shown in 
our chapter on receiving sets. 

For really good results,-as far as a home-made set 
is concerned, it is necessary to employ the regenerative 
arrangement. This arrangement, as has already been 
described elsewhere in this work, is virtually a self-am¬ 
plifier, and adds a great deal to the efficiency of the re¬ 
ceiving set. 

One of the very best yet simple receiving arrangements 
which has come to the attention of the author and which 
he has constructed for his own experimental use, is shown 
in the accompanying drawings. It is a verv simple form 
of two-circuit receiving set, using a plate variometer 
for the feed-back or regenerative agent. 

First of all, it is necessary to construct the main tuning 
member, which is simply a mailing tube measuring 3^2 
inches in diameter by 4 inches long, on which two wind¬ 
ings are carefully wound. The first winding consists of 
twenty turns of No. 20 B. & S. gauge double cotton cov¬ 
ered wire, wound close together, of course, while the sec¬ 
ond winding, starting one-eighth away-from the end of 
the first winding, consists of 40 turns of same sized wire, 
also wound close together. The windings should be held 


Assembly of vacuum tube receiving set and how it is connected with the ground and antenna The 
location and connections for the lightning switch and lead-in insulator are also shown. * 






























































296 


RADIO FOR EVERYBODY 


in place simply by making holes in the cardboard tube 
and passing the ends of the windings through these holes. 
Under no circumstances should the windings be varnished 



How the fixed winding of the variometer 
is made. A frame work is built up with 
sheet fiber on a square form, and held 
together with shellac or glue. The wind¬ 
ing is placed on this form, as shown. 

or shellacked, as this introduces certain undesirable char¬ 
acteristics. Both windings are fixed, their wave length 
values being altered by variable condensers as shown in 
the accompanying wiring diagram. 

The variable condensers may he of the home-made 
variety, using the book type already referred to in the 
previous set. Two such condensers will be necessary, 
and it is well to make them of good size so that they 
will have ample capacity. One condenser is placed across 
the primary winding—or in series with it if the wave 
length of the antenna-ground circuit is to he reduced— 
while the other is placed across the secondary winding. 










RADIO FOR EVERYBODY 


297 


A fixed condenser must be constructed. This consists 
of nothing more formidable than a number of sheets of 
tin foil separated by pieces of paraffined paper. A good 
condenser may be made by cutting ten pieces of tin foil 
so that they will measure one inch wide by three inches 
long and cutting eleven pieces of paraffined paper so that 
they measure one and one-quarter inches wide by two 
and one-half inches long. The paraffined paper and the 
tin foil sheets are assembled in staggered order as shown 
in the accompanying sketch. The pile of tin-foil and 
paraffined paper can be placed between two pieces of 
cardboard and held together by means, of a rubber band 
or piece of thread wrapped around the cardboard end 
pieces. 

The grid leak had best be purchased, for it is a rather 









































298 


RADIO FOR EVERYBODY 


difficult thing to make even though it does not consist of 
more than a pencil line drawn on a piece of good paper 
and clamped between two copper washers. If the con¬ 
structor wishes to build the grid leak as well as other 
parts of the set, he is welcomed to try it, although it 
would seem that since this item costs but 50 cents to buy 
it ready made—and properly made—it is best not to 
waste time and effort in trying to construct a grid leak. 

Then we come to the filament rheostat. Here again, it 
is best to purchase a manufactured filament rheostat, 
which may run all the way from 75 cents to $2.00, depend¬ 
ing on how well it is made. The tube socket must 
also be purchased, representing an outlay of from 75 cents 
to $2.00, depending on the type selected. 

The “A” battery is the filament battery, and consists 
of either a dry battery, preferably composed of ten dry 
cells arranged in series multiple as depicted on page 297,, 
or a 6-volt 20-ampere-hour storage battery. The “B” 
battery is the high-voltage battery for the plate circuit. 
It consists of a single block of battery supplying 22 I / 2 - 
volt current. The telephone receivers may be a single 
receiver or a regular head-set, according to taste—and 
pocktbook. Finally, there is the variometer used as the 
feed-back device. 

The variometer had best be purchased, for it is a difficult 
instrument for the home constructor to tackle. Of course, 
a variometer may be constructed, because it consists 
simply of a fixed winding and a corresponding turnable 
winding. But the point in the case is to make a variom¬ 
eter that will work properly, and that requires a little ex¬ 
perience and skill. 

However, if the builder insists on constructing the 
variometer, he may do so. A simple design is shown in 
the accompanying sketch. It consists of a stationary 
wooden frame, built up in the manner indicated, and a 
movable frame. Now the stationary winding is placed on 
a form made of fiber strip, shellacked together to make 
it strong. This frame, with its winding, is placed inside 
the stationary frame. The movable winding, on the other 


BAILING 

TUBE 



40 TURNS 


20 TURNS 


CARDBOARD 


TINFOIL 



TINFOIL 


PAPER 

SEPARATORS 



How the fixed coupler is made, and the construction 
of the small fixed condenser. The first drawing 
shows the mailing tube with twenty turns and forty 
turns for the primary and secondary windings. The 
second drawing shows the assembly of the fixed con¬ 
denser. The third shows a side view of the assembled 

condenser. 
























































































300 


RADIO FOR EVERYBODY 


hand, is wound on the movable form, as indicated. Each 
winding should consist of 60 turns of No. 20 double 
cotton covered wire. No nails should be used in making 
this instrument, glue or wooden pegs being used through¬ 
out. A suitable shaft should be provided, so that the 
movable coil can be turned by means of a handle. A dial 
can be drawn, with graduations from 1 to 100, or a dial 



How the various components of the simple regenerative set 
are connected together. A—antenna; G—ground; P—primary; 

S—secondary; VC1—primary condenser; VC2—secondary con¬ 
denser; FC—fixed condenser; GL—grid leak; YT—detector 
tube; A—filament battery; B—“15” or plate battery; R—rheo¬ 
stat; T—telephone receivers; V—variometer for feed-back. 

and handle can be purchased from any radio supply house. 
However, after all is said and done, the best results will 
he obtained by purchasing a variometer, since this is a 
rather difficult instrument to construct—and construct 
right. 

The set is arranged as shown in our assembly drawing. 
It is a simple set to operate and permits of extremely 
sharp tuning. The regenerative arrangement makes for 



























Graphic presentation of the simple regenerative receiving set as it appears when assembled and wired. It is 
left to the constructor’s ingenuity to assemble the units in a neat cabinet for the sake of compactness espe¬ 
cially if bought variometer and condensers are employed. 



















































































302 


RADIO FOR EVERYBODY 


excellent results, so that this set will receive from radio¬ 
phone broadcasting stations over 100 miles away under 
favorable circumstances, without an amplifier. With an 
amplifier, which may be readily constructed by purchasing 
the necessary components and assembling them in the 
manner indicated by the wiring diagrams in the chapter 
dealing with amplifiers, the range may be materially in¬ 
creased. 


Chapter XII 

LATER-DAY RADIO DEVELOPMENTS 
AND HOW TO APPLY THEM TO 
BROADCASTING RECEPTION 

Radio moves rapidly. When the first edition of this 
hook was being written during the early months of 1922, at 
a time when radio broadcasting was still in its infancy, 
it was not a difficult matter to study and describe the exist¬ 
ing methods of reception, as well as to direct attention 
to the various types of receiving sets. In those early days 
the greatest interest centered about complete receiving 
sets; indeed, those who were drawn into radio were pre¬ 
pared to purchase almost any set at almost any price. 

Today, but a short while later, things are quite different. 
There have been many improvements in the instruments as 
well as in the methods employed. It seems that daily some 
variation of an existing method or an entirely new method 
of reception is offered to the radio fraternity. In truth, 
it is this constant succession of improved and new receiv¬ 
ing methods which has made radio so interesting and 
which has caused so many radio novices and amateurs to 
prefer separate instruments and parts to complete receiving 
sets. While there is ample demand for good receiving 
sets which require merely an aerial and ground connection 
to be ready for actual reception, there are more and more 
radio devotees “building their own.” 

So in this last chapter of this revised edition of our 
book we shall endeavor to review the various later-day 
developments in radio, and to tell how these developments 
may be applied to broadcasting reception. .We shall deal 


304 


RADIO FOR EVERYBODY 


with solid practice rather than abstract theories, since the 
latter task may well be left to other works on radio. 

The WD-11 Tube —A* Vacuum Tube Without the 

Usual Trouble 

There can be no doubt that the foremost development in 
recent radio history, so far as broadcasting is concerned, 
is the introduction of the dry-cell vacuum tube. The best 
known type of dry-cell tube is the Radiotron WD-11, 
although there are others on the market and about to be 
introduced. This tube is an efficient vacuum tube, designed 
for operation on dry cells instead of the usual troublesome 
and expensive storage battery. In truth, the dry-cell 
vacuum tube makes it possible to substitute a vacuum tube, 
with all the added efficiency which that entails, for the 
usual crystal detector in inexpensive sets. More than 
any other factor, no doubt, the WD-11, as well as other 
dry-cell tubes, has made for remarkable results for home¬ 
made radio sets. 

The usual vacuum tube generally burns quite brightly— 
almost an incandescent white—because the tungsten fila¬ 
ment emits a voluminous flow of electrons only when it is 
heated to a high degree. The secret of the dry-cell tube, 
on the other hand, is the coating of the filament with 
a special oxide so that a voluminous flow of electrons will 
take place at a low temperature. Thus, far less current 
is required to obtain a sufficient electronic flow, and the 
tube glows no brighter than a dull red and consumes a 
quarter ampere or less in marked contradistinction to 
somewhat over one ampere at five or six volts for the 
usual vacuum tube. 

A single 2234-volt “B" battery unit will prove quite 
satisfactory in the plate circuit of the WD-11, although 
potentials up to 80 volts may be applied, especially if 
volume of sound is desired. Despite the compact arrange¬ 
ment of the electrodes in the WD-11 tube, it is reasonably 
free from tube noises. The WD-11 has a base which. 


RADIO FOR EVERYEODY 


305 



though consisting of four prongs, differs considerably from 
the usual vacuum tube. A special base has been used in 
other to differentiate the tube from tubes of a higher 
voltage, so that it could not be 
inserted by mistake in a regu¬ 
lar circuit with a six-volt “A” 
battery potential. Special 
sockets are available for the 
WD-11 tube; furthermore, 
special adapters may be used 
to fit the WD-11 tube to any 
standard receptacle or socket. 

This dry-cell tube comes in 
but one size and kind. There 
is but one tube for detection 
and amplification. However, 
being a “hard” tube— which 
means that its degree of 
vacuum is quite high—it works 
well as a detector and very well 
as an amplifier. Its current 
consumption is given as 0.20 
ampere, the terminal voltage 
as 1.1 volts. The “B” battery 
for the detector should be 22.5 
volts, the amplifier takes 45 
volts. For detection, a grid 
condenser of .00025 mfd. 
should be used. The grid leak 
should be 2 megohms. For 
amplifying it is best to use 
transformers which are recom¬ 
mended by their manufactur¬ 
ers for use with the WD-11 
tube. 

While the WD-11 is a dry¬ 
cell tube, the fact remains that The wu-n tube, which oj»er- 
if operated on a single dry cell n,es 0,1 " drv ba * tery 








306 


RADIO FOR EVERYBODY 


it will soon exhaust it. The better practice is to use two 
dry cells for each WD-11 tube, so that the drain is then 
shared by both cells and it is not so strenuous on each 
cell. The dry cells should be connected in parallel—that 
is, carbon to carbon, and zinc to zinc, maintaining the 
voltage the same but doubling the amperage available. 
If two WD-11 tubes are used, then four dry cells, con¬ 
nected in parallel, should be used, and so on. Three cells 
for each tube is even still better, since the drain on each 
cell is reduced materially. Dry battery manufacturers 
have come out with convenient dry battery units which 
contain two or more cells in a single compact case, with 
the two terminals ready for use. These compact units 
have several advantages over the group of individual 
cells which must be connected together. 

Dry-Cell Receiving Sets: The Flivvers of Radio 

Had it not been for the introduction of the dry-cell 
tube, we should not have the present home-made receiving 
sets which abound in such great numbers throughout the 
land. For it is true that at a distance beyond 25 to 35 
miles, the average crystal detector is of little use so far 
as broadcasting reception is concerned. With the dry-cell 
tube, on the other hand, it is possible to receive at distances 
up to several hundred miles under the usual conditions, 
and up to thousands of miles under the excellent conditions 
of crisp winter nights. 

So we now come to the interesting and useful discussion 
of inexpensive receiving sets making use of dry-cell tubes. 
The receiving sets described in the previous chapter can 
well be adapted to the dry-cell cell. For that matter any 
crystal receiving set can be converted into a vacuum tube 
set by using the dry-cell tube. One stage or more of 
amplification can be added to any crystal detector, if so 
desired. The accompanying diagram shows how the dry¬ 
cell tube replaces the usual crystal detector in a simple 
circuit. 


RADIO FOR EVERYBODY 


307 


While the vacuum tube used in the ordinary manner 
will give considerably better results than the crystal detec¬ 
tor, one may as well get all that can be obtained, since the 
cost is about the same. It is a simple matter to use a 
regenerative arrangement, whereby the tube, by feeding 
back a part of its plate current energy back to the grid, 
gives far louder signals in the telephone receivers. The 
two most common methods of Obtaining simple regen¬ 
erations are first, the inductive coupling of the plate circuit 



How the WD-11 tube, or any other dry cell tube, is connected 
with dry cell and “B" battery, as well as telephones, in place 
of the crystal detector. The grid leak and grid condenser are 
not shown in the upper left-hand connection to the tuner. 


to the grid circuit by means of a small coil known as the 
tickler, placed near the winding of the grid circuit, and 
secondly, some means of tuning the plate circuit so as to 
bring it into resonance with the grid circuit. 

The simplest means of 'obtaining regeneration is to use 
a standard vario-coupler as a single-circuit tuner and 
tickler. Instead of using the rotating member or rotor 
of the vario-coupler as the secondary of the receiving set, 
in the simplest regenerative tuner the rotor is used as a 
tickler. The diagram on page 309 shows the arrangement 
of the various pieces of apparatus, with the secondary 
of the vario-coupler used as the tickler. The same general 
arrangement applies to the all-wave coupler and to the 
Westinghouse single circuit tuner, now available as a part. 

While the usual vario-coupler will do for a single-circuit 




























308 


RADIO FOR EVERYBODY 


regenerative tuner, it is perhaps more advisable to use a 
so-called 180 deg. vario-coupler. This type has the rotor 
winding arranged at an acute angle to the shaft, so that 
the coil not only turns about but can be rotated from a 
position absolutely in line with the stator winding to one 
at right angles, so as to make for a maximum range of 
coupling. The ‘‘ball” type of stator, on the other hand, 
gives a more limited variation, since all that can be altered 
is simply the direction of both windings and not their 
relative alignment. At any rate, the “ball” type of stator 
will do as a tickler, although care should be taken to see 
that there is not too much space between the windings. 
In case the “ball” rotor is at the end of the stator winding 
tube, and the set fails to regenerate properly, it may be 
well to take off the winding on the stator and rewind it 
with twice as much wire of a smaller size. Also, if the 
set fails to regenerate satisfactorily, it is well to change 
about the connections leading to the rotor. 

In such an arrangement., a fixed condenser of .001 
micro-farad is placed across the telephones and the “B” 
battery. However, in view of the considerable capacity 
effect in the usual long telephone connecting cord, a con¬ 
denser is often unnecessary. If the by-pass condenser 
does not improve the regenerative effect, it may be dis¬ 
pensed with. When an audio-frequency amplifier is 
employed the by-pass condenser will be found to be more 
effective. 

With the usual dry-cell tube, especially the WD-11 type, 
the grid leak should be of 2 megohms rating, and the grid 
condenser of .00025 micro-farad capacity. It is well to 
use good grid leaks and good grid condensers. The little 
paper affairs sold for ten cents or so are of poor quality 
and may often be the cause of poor results. It is far better 
to use mica condensers so that this feature of the receiving 
set can at least be relied upon. 

It will be noted that in most of these so-called “flivver” 
sets a variable condenser is employed in the antenna-ground 
circuit. The condenser serves to vary the wave length 


RADIO FOR EVERYBODY 


309 


in a very gradual manner, and makes for accurate tuning. 
If the antenna is 100 feet long or over, the condenser is 
placed in series with the antenna or the ground connection 
—it does not matter which one is interrupted by the con¬ 
denser. On the other hand, if a short antenna is used, say 
one of 75 feet or less, then the condenser should be placed 
across the stator winding, or in parallel. Remember 
always, a condenser in series with a winding cuts down the 
wave length; a condenser in parallel or across a winding 
increases the wave length. Taps are generally provided 
on the usual vario-coupler, and these are brought to a 
multi-point switch. However, if a large variable con- 



Wiring diagram for a single circuit regenerative receiver, using 
vario-coupler as the tuner: VC—43-plate variable condenser, 
p—primary of vario-coupler ; S—secondary. SW—switch in vario- 
coupler primary. GL—Grid leak, Vsj to 2 megohms. GC- grid 
condenser .00025 micro-farad. R—1 ohm rheostat. FC—fixed 
condenser .001 micro-farad. G—ground. 


denser, say one of 43 plates, is placed in series with the 
antenna-ground circuit, it will be found that the full wind¬ 
ing can generally be used and the variable condenser can 
vary the wave length of the full winding within wide 
limits, thus eliminating switch taps. 






































310 


RADIO FOR EVERYBODY 


Still More About the Flivver Sets 

Variable condensers are employed because they do the 
work for the least expense. Variometers are better, but 
they cost more money. An excellent “flivver” arrangement 



condenser for tuning: V—variometer. VC—43-plate variable con¬ 
denser. GL—grid leak, 2 megohms. GC—grid condenser .00025 
micro-farad. A—antenna. G—ground. This arrangement is said 
• to give remarkable results, despite its utmost simplicity, and 
numerous records have been established with it. 

consists of a single variometer and a variable condenser 
for the tuning end, and the vacuum tube and its acces¬ 
sories, as shown in our accompanying illustration. This 
tuning arrangement will cover the broadcasting wave length 
band when a 43-plate variable condenser is used. If the 
builder prefers, a No. 50 duo-lateral coil—one of the 
several compact inductance coils on the market—may be 
used as a fixed inductance instead of the variometer. The 
variometer, however, makes for much finer tuning and is 
preferable in locations where there is considerable inter¬ 
ference. With a 100-foot antenna such a set will receive 
from radio-phone stations 1,000 miles distant, especially 
if a one-stage amplifier is coupled to it. 




























RADIO FOR EVERYBODY 


311 


So far we have dealt with the inductive method of 
regeneration. Perhaps better results and certainly 
simpler manipulation may be obtained by using the tuned- 
plate-circuit method, which is shown in the next hook-up. 
Here two variometers are employed, one for the antenna- 
ground circuit in connection with a variable condenser, 
and the other in the plate circuit, as shown. The second 
variometer is used to tune the plate circuit so as to feed 
energy back into the grid. This circuit is well worth the 
additional cost of the second variometer, because much 
better results can be obtained. 

The receiving circuits given so far are especially suited 
to the dry-cell tubes. However, all the standard circuits 
described in the other parts of this book and intended 
primarily for use with standard vacuum tubes, may be 
utilized. The WD-11 dry-cell tube works very well, in¬ 
deed, and great distances are reported by users of this 



Simple receiving circuit making: use of two variometers: V1 
variometer. VC—43-plate variable condenser. GL—2 megohm 
grid leak. GC—grid condenser, .00025 micro-farad. V2—vario¬ 
meter. FC—fixed condenser, .001. This condenser may or may 
not be required, according to circumstances. 

tube. Still, it is a fact that the dry-cell tube is not quite 
so good as the standard tubes, because of its necessarily 
more limited output. 
































312 


RADIO FOR EVERYBODY 


Recent Vacuum Tubes and Their Meaning 

While dealing with vacuum tubes it is as well to sur¬ 
vey what has been done of late in developing new tubes. 
Since the first edition of this work was prepared, several 
new types of tubes have been placed on the market and, in 
a short while, many new types are bound to put in an 
appearance. Some of the basic patents covering vacuum 
tubes have expired, removing the restrictions which have 
heretofore barred certain manufacturers from turning 
out tubes. 

The Radiotrons UV-200 and UV-201, detector and 
amplifier types, respectively, together with the WD-11, 
still lead in popularity. If anything, the WD-11 is now 
the most popular, because, unlike the Radiotrons UV-200 
and UV-201, it requires no storage battery. But the 
UV-200 and UV-201, calling for a terminal potential 
of 5 to 6 volts on the filament and a current consumption 
of 1.1 amperes, are rather expensive to operate, especially 
when several tubes are employed at one time. In many 
of the more elaborate sets of the present day as many 
as five tubes are employed, such as two for radio-fre¬ 
quency amplification, one for the detector, and two more 
for audio-frequency amplification. Five UV tubes, re¬ 
quiring 1.1 amperes each, drain the storage battery at the 
rate of 5.5 amperes per hour. Thus a 60-ampere-hour 
storage battery will last about ten hours in constant use, 
and it has to be recharged at frequent intervals. 

Little wonder, therefore, that the multiplicity of vacuum 
tubes in standard sets has called for a more economical 
type of tube. This demand has been answered by the 
introduction of the Radiotron UV-201-A during the 
recent past. The UV-201-A is a high vacuum tube suit¬ 
able for detection, radio-frequency amplification, and 
audio-frequency amplification. It contains a new kind of 
tungsten filament, the characteristics of which are long 
life, low power consumption and low operating tempera¬ 
ture, and it consumes only one-quarter (0.25) ampere. 


RADIO FOR EVERYBODY 


313 


The leading features of this remarkable tube, which 
sells at a considerably higher price than the usual run of 
tubes, are : (1) I he electron emission from the filament 

averages five times that of the ordinary amplifying tube 
and it therefore gives improved loud-speaker operation. 
(2) The filament energy of this tube is one-quarter ampere 
and in the case of a one-tube set it may be operated by 
four dry cells in series. (3) This tube is an excellent 
detector, although it does not equal the UV-200 for this 
purpose. The UV-200, as stated elsewhere, is a “soft” 
or gas-content tube. (4) As an audio-frequency ampli¬ 
fier it delivers at least 50 per cent more energy. (5) 
The tube has a very high vacuum. This ensures uniform 
characteristics and quiet operation. (6) In its operation 
as a detector or amplifier in a radio receiving set the re¬ 
sults are exceptionally independent of filament adjustment. 
Critical adjustments of grid leak and condenser are not 
required. (7) The UV-201-A can be used in any equip¬ 
ment at present using the ordinary tube, and it will give 
improved results, except as a detector. 

The following notes about the UV-201-A may be of 
interest: If the filament voltage is supplied by a 6.0-volt 
battery, the resistance of the filament rheostat should be 
at least 4 ohms. Filaments should always be operated 
at the lowest current which will give satisfactory results. 
If by accident excessive filament or plate voltage is applied 
to the tube, the tube may lose its activity. Ordinarily, 
activity may be restored by lighting the filament at rated 
voltage for ten to twenty minutes with plate voltage off. 
Failure of the filament is seldom due to actual burn-out 
unless very high voltage is applied. The end of useful 
life is indicated by a decrease in the electron emission. 
Care should be taken to prevent the plate voltage from 
being accidentally applied to the filaments. Tubes should 
be removed from the sockets when connections are 
changed. The tubes should be mounted on cushion or 
spring supports to prevent noise from vibration, since 
they are microphonic or “noise reproducing.” It is 


314 


RADIO FOR EVERYBODY 


.00025 M.F. 



Special connections for the UV- 
201-A when used as a detector. 


GRID 


PLATE 


preferable to mount the tubes vertically. The bulbs are 
often discolored during the process of manufacture. This 

has no effect whatever on 
the operation of the tubes. 
The life of the tube is 
usually ended by a decrease 
in electron emission. This 
is indicated by an increase 
in the filament voltage re¬ 
quired for satisfactory re¬ 
sults. 

When used as a detector, 
it is preferable to connect 
the grid return of the UV- 
201-A to the positive side of the filament exactly as 
shown in the accompanying hook-up. A grid condenser 
of .00025 microfarads and a grid leak of 2 to 5 megohms 
are recommended. Critical 
adjustments of grid leak 
and condenser are not re¬ 
quired. The best plate 
voltage for detection is ap¬ 
proximately 40 volts. 

When used as an ampli¬ 
fier, the UV-201-A works 
at its best when the fila¬ 
ment rheostat is placed 
in the negative lead from 
the “A” or filament battery, 
and when the return lead from the grid circuit is con¬ 
nected to the negative side of the “A” battery and not to 
the negative side of the filament. The connections shown 
in the second diagram will also work satisfactorily. 
For the best results the negative grid bias voltage should 
be increased with increase in plate voltage. In general 
the following grid bias voltages are suitable: 40 volts on 
plate, 0.5-1.0; 60 volts on plate, 1.0-3.0: 80 volts on plate, 
3 0-4.5; 100 volts on plate, 4.5-6.0. The grid bias is a 



Satisfactory connections for the 
UY-201-A when used as an 
amplifier. 

























RADIO FOR EVERYBODY 


315 


negative potential applied on the grid either through the 
use of a potentiometer, or by means of a third battery 
sometimes called the “C” battery. 

The “C” Battery and the Biasing of the Grid 

At this point it is well to interrupt our general dis¬ 
cussion of new vacuum tubes and to say a few words 
regarding the “C” battery and the biasing of the grid as 
applied to quality amplification. The widespread use of 
loud-speakers has brought about high amplification; and 
high amplification, in turn, is apt to introduce distortion. 
In order to reduce distortion in high amplification it is 
usually necessary to resort to grid biasing. 

The amplification of a set can be materially increased 
by the careful adjustment of the amplifier potentials. 
Since the amplifier tube operates on the principle of grid 
voltage control, the plate of the tube must be maintained 
positive in order that the electrons emitted by the filament 
will flow to the plate. The grid is maintained negative. 
When voltages over 50 are used on the plate, the grid 
becomes less effectively negative and current flows from 
the filament to the grid. This produces a voltage drop 
from the grid to the filament, which reduces the voltage 
effective for amplification. In order that the grid may be 
maintained negative, a dry battery of from 1 to 10 volts 
should be connected in the lead connecting the inside of 
the transformer secondary to the filament battery. The 
negative side of the biasing battery should be connected 
to the transformer and the positive side to the negative 
terminal of the filament battery. Where plate voltages 
only of the order of 50 are used, sufficient biasing may 
be obtained by means of a potentiometer connected as 
shown in the diagram on page 316. If the potentiometer 
is not used, the inside of the secondary of the amplifying 
transformer should be connected directly to the negative 
side of the filament battery. 

The lead from the outside of the amplifying trans- 


316 


RADIO FOR EVERYBODY 


former secondary to the grid of the tube should be kept 
as short as possible and away from other wires, particular¬ 
ly those of the plate circuit. By so doing the tendency 
to howl will be greatly minimized. When two or more 
transformers are used for multi-stage amplification, it is 
best to place them at right angles so as to reduce inter¬ 
action between their fields. The use of a grid leak of 
about one megohm connected between the grid and the 



How to wire up an audio-frequency amplifier in order to obtain 
clear tones in telephone receivers or loud-speakers, especially 
when using: limited voltagre for the plate circuit. It w r ill be noted 
that a potentiometer is employed for biasing: the grrid. If voltagres 
over 50 are employed, a dry battery of 1 to 10 volts should be 
inserted in the lead from inside of transformer secondary to 

filament battery. 

negative filament terminal will improve the quality of 
received telephone signals. This is particularly true with 
high-pitched notes. The leak also adds desirable damping 
to the circuit, thus further tending to prevent howling. 

More About Recent Vacuum Tubes 


One of the first evidences of the expiration of the 
original Flemming valve patent, which prevented un- 

























RADIO FOR EVERYBODY 


317 


licensed manufacturers from placing tubes on the market, 
are the new DeForest DV-1 and DV-6 tubes. Both types 
are hard pumped, but because of their inherent charac¬ 
teristics either type will work as detector or amplifier. 
These tubes require an amount of current in the filament 
which is about one-half that required by the usual standard 
types. This means a saving on the storage battery or 
dry battery, and an increase in the life of the tube, because 
the filament is burned at a lesser degree of brilliancy. 
1 he DeForest tubes are small in size and exceedingly 
neat in design, making them especially suitable for compact 
sets and for exposed mounting. The extremely short 
parallel lead wires in the tube, combined with the high 
resistance base, makes these tubes ideal for radio-fre¬ 
quency amplification. The DeForest tubes are manufac¬ 
tured by a special method of bombardment—a phase in 
the exhausting of the tube so as to remove as much air as 
possible—so that the filament is not unduly heated. The 
bombardment is by high frequency inductance around the 
outside of the tubes, which heats the elements without de¬ 
teriorating the filament, according to the makers. 

Now as for the meaning of both the DV-1 and the 
DV-6 designations. The DV-1 is a dry-cell tube. It 
operates on a filament potential of 1 to 1.5 volts, and 
consumes .2 ampere. The plate voltage should be 40-60 
volts. The filament is of platinum, coated with an oxide. 
Filament, grid, and plate are arranged horizontally, fol¬ 
lowing the usual European practice. A standard four- 
prong base, heavily nickel-plated, is provided. 

The DV-6, on the other hand, is a storage battery tube. 
It operates on a filament potential of from 3 to 5 volts, 
with a current consumption of .5 to .7 volt. When used 
as a detector, the plate voltage should be about 45 volts 
for best results. As an amplifier the plate voltage should 
be between 60 and 100 volts, depending on the charac¬ 
teristics of the particular tube used and the circuit. 

Another tube is RAC audion, also known as the Myers 
tube. This type is quite different from any other tube, 


318 


RADIO FOR EVERYBODY 


in that it is constructed along the general lines of a cart¬ 
ridge fuse and fits into a holder that looks quite like the 
usual cartridge fuse holder. The Myers tube has a small 
cylindrical plate, helical grid, and a straight filament. 
It operates on a filament potential of 4 to 5 volts, and a 
plate potential of 45 to 90 volts and over. The author 
has employed Myers tubes with excellent results for ampli¬ 
fication ; indeed, for loud-speaker operation these tubes are 
quite remarkable, taking an unusually high plate voltage 
without ionization—breaking down the vacuum in the 
tube, which glows with a blue light and no longer ampli¬ 
fies properly until the filament is extinguished, restoring 
the original conditions. 

The Western Electric Tubes—Rare Tubes Indeed 

Due to one of the peculiarities of radio patents and 
licensing arrangements, the Western Electric Company 
is not licensed to sell various types of tubes which it 
manufactures to amateurs, with the exception of one tube, 
type 216-A, which is sold as initial equipment and for 
replacement in connection with the 10-A loud-speaking 
receiver made by that company. Yet the fact remains 
that the Western Electric Company has gone further in 
the development and manufacture of the highest grade 
vacuum tubes than any other organization. More is the 
pity! 

At any rate, the various Western Electric tubes have 
a certain amount of interest to radio amateurs, especially 
since two Western Electric types, the so-called VT-1 and 
the VT-2, have been sold to amateurs by radio stores 
as the result of the disposal of large stocks of these tubes 
by the Army and the Navy. 

The type J Western Electric tube is popularly known 
as the VT-1 from its Signal Corps designation. It is 
intended primarily as a detector tube, although it can be 
used as an amplifier. It operates on a normal filament 
current of 1.1 amperes, and a normal filament voltage of 


RADIO FOR EVERYBODY 


319 


2.0 to 4.0 volts. The normal plate potential is 17 to 40 
volts. The filament is oxide coated and burns a very 
dull red. The filament current should not be allowed to 
exceed 1.3 amperes, for otherwise the useful life of the 
tube will be materially shortened. This tube represents 
exceedingly neat construction, quite characteristic of West¬ 
ern Electric tubes. 

The Type E is popularly known as the VT-2. It was 
designed as a power tube to generate and modulate radio- 
frequency oscillations. It may also be used as an ampli¬ 
fier. The normal filament current of this tube is 1.35 
amperes. The normal filament voltage is 6.5 to 7.5 volts. 
The normal plate voltage (with zero grid voltage) is 
200 volts. If the grid is maintained at a negative poten¬ 
tial, the plate potential can be safely raised above the value 
given by an amount equal to the product of the amplifica¬ 
tion constant and the negative grid potential. The plate 
voltage used with the grid at 20 volts negative, is 350 
volts. If the filament current is allowed to exceed 1.4 
amperes, the useful life of the tube will be materially 
shortened. 

The type 216-A tube is used in the 10-A loud-speaker 
of the Western Electric Company. It is designed for 
use as an amplifier and is much better for this purpose 
than either the type J or type E tubes. The filament 
is designed to secure the necessary electronic emission 
with low filament temperature. This feature ensures, 
under normal operating conditions, long life and minimum 
filament power consumption. The normal filament current 
is obtained with a potential of 6 volts at the terminals of 
the amplifier. With normal current the filament should 
grow dull red, and it goes without saying that the filament 
should not be allowed to glow brightly. The normal 
filament voltage is 6 volts, and the normal plate voltage 
100 to 130 volts. 

The type N tube is popularly known as the Peanut Tube. 
Indeed, it is the true peanut tube, although the WD-11 
and other tubes are erroneously referred to as peanut 


320 


RADIO FOR EVERYBODY 


tubes by the uninformed. This type N tube was developed 
to require a minimum amount of power for the filament 
circuit, so that a dry cell can be used for this purpose 
with reasonably long life. It is suitable for a detector, 
radio-frequency amplifier, or an audio-frequency ampli¬ 
fier within the limits of its power output. It is an ex¬ 
ceedingly small tube—the smallest tube extant, for that 
matter, and has a special base which calls for a special 
receptacle. 

The Donle Tube, Which Gets Along Without 

Regeneration 

After several years’ research work Efarold P. Donle, 
radio engineer of Meriden, Conn., has developed a re¬ 
markable vacuum tube, which bears his name. It varies 
considerably from standard vacuum tube practice, and 
as these lines are being written it is still too young to 
prophesy just what will be the extent and the value of 
its application. This much is certain, however: the Donle 
tube gives a signal strength, when used in a plain circuit, 
greater than a single-tube regenerative set. Therefore, 
it does away with regenerative receivers and makes for 
a minimum of interference with other receivers. In 
crowded sections, such as large cities, the interference set 
up by numerous regenerative sets located close together 
has become well nigh unbearable. So the Donle tube 
has one great feature to recommend it at the very start. 

The accompanying diagram shows the general arrange¬ 
ment of the electrodes in the Donle tube. F is the fila¬ 
ment ; A the anode, which is of metallic sodium placed 
in the bottom of the tube, and H the heater. A short 
length of resistance wire is cemented to the outside of 
the glass directly underneath the anode. This heater main¬ 
tains the anode at its proper operating temperature. C 
is the collector, made of sheet metal bent into a U 
shape and positioned above the filament with its side to¬ 
ward the anode. 























































































322 


RADIO FOR EVERYBODY 


The tube is connected to a two-circuit tuner with one 
of its secondary terminals connected to the collector elec¬ 
trode of the tube and the other to a contact operating on a 
resistance connected directly across the filament battery 
terminals. The remainder of the' circuit is connected as 
any simple circuit. For efficient operation the adjustment 
of the collector potential along with the usual variation 
of capacity and coupling, makes the tube function. There 
is no critical point of potential of the “B” battery. It 
may be varied between ten and thirty volts without ap¬ 
preciable effect on the signals received. Inasmuch as the. 
Donle tube when connected in a plain non-regenerative 
circuit gives signal strength as great as the response from 
a regenerative tube using non-oscillating regeneration at 
its maximum point, it is evident that it is superior for 
radio telephone purposes. The usual regenerative tube, 
when pushed to the point of extreme loudness, gives dis¬ 
torted music or speech. 

The Trend in Vacuum Tubes 

Constant progress is being made with vacuum tube 
design. The trend is toward more economical tubes, such 
as the WD-11, the Radiotron UV-201-A, and the De 
Forest DV-1 and DV-6. Other tubes of the coated 
filament type are bound to appear on the market in a 
short while; in fact, the General Electric Company has 
a small dry-cell tube which is employed in one of the 
several compact radio telephone receiving sets made by 
the organization. The standard tubes with their heavy 
current consumption must ultimately make way for the 
newer tubes with low current consumption, not only in 
order to eliminate the storage battery, but, in some in¬ 
stances, to make the charge of the storage battery, which 
may still be used, last longer when many tubes are em¬ 
ployed at one time. 

It has been hoped that the time would come when 
vacuum tubes could be operated on 110-volt commercial 


RADIO FOR EVERYBODY 


323 


current, not only dispensing with the storage battery 
tor the filament current, but also with the “B” battery 
^. r ^? e pl a t e circuit. Considerable experimenting along 
this line has been undertaken by the U. S. Bureau of 
Standards and by various radio research organizations, 
but so far the results are of mild interest only to the radio 
novice. The cold fact is that it requires more equipment 
and more trouble to utilize the usual lighting current for 
vacuum tubes than it does to use “A” and “B” batteries 
and recharging outfits. There has lately appeared on the 
market a power amplifier operating on lighting current. 
The filaments are operated on the lighting current, but 
“B” batteries are still used for the plate circuits. Radio 
engineers have predicted that the day may come when 
vacuum tubes, operating directly on lighting current, will 
be feasible for amplification purposes. Considerable work 
has already been done along this line and the idea is by 
no means fantastic. 

For the time being, however, we are still committed 
to “A” batteries and “B” batteries, and to dry cells, 
which must be constantly bought, and rechargers which 
must be constantly operated to recharge our storage bat¬ 
teries. 

The Armstrong Super-Regenerative Circuit 

One of the great steps forward in the recent radio art 
is the Armstrong super-regenerative circuit, which is now 
represented by numerous interesting modifications, some 
of them bearing the names of their originators. The 
Armstrong super-regenerative circuit is an improvement 
on the usual regenerative circuit, also invented by Arm¬ 
strong. If the reader is familiar with the operation of 
the usual regenerative receiver, which operates on the 
principle of feeding back plate variations, which are 
many times as powerful as the original grid current 
variations, back to the grid so as to raise the grid varia¬ 
tions to a still greater degree, so that they will in turn 


324 


RADIO FOR EVERYBODY 


cause still greater plate variations, and so on, he will re¬ 
member how the signal strength is steadily built up by 
the tickler as the feed back is increased until suddenly the 
signals become “mushy” and the tube squeals. This 
state of affairs indicates that the oscillating point has been 
reached, and that the feed-back action has been too power¬ 
ful. T he tube is now operating as a generator of waves, 
and no longer can be used as a detector for clean cut 
radio telephone signals. 

Now any operator of a regenerative set knows how 
aggravating it is to have the tube oscillate just at a point 
where the signal strength has almost reached the de¬ 
sired magnitude. If only the tube would hold off oscil¬ 
lating for a few more points on the tickler dial! 

Well, that is precisely what the Armstrong super- 
regenerative circuit accomplishes. It “holds off” the 
oscillating point, so that the feed-back action is carried 
far beyond the usual degree and extremely loud signals 
are obtained with the ordinary tube. It now becomes 
possible to obtain as loud response from single tube, using 
the Armstrong super-regenerative arrangement, as would 
be possible ordinarily with three tubes in a more con¬ 
ventional hook-up. 

The simplest Armstrong super-regenerative circuit is the 
single-tube receiver shown in the accompanying diagram. 
Here the single tube performs simultaneously the func¬ 
tions of regenerator, oscillator, detector, and amplifier. 
Although the results are truly astounding, the fact remains 
that the circuit requires extremely careful handling by 
the experimenter who will have to learn the delicate ad¬ 
justments by experience. It is not a simple matter to 
master the single tube super-regenerative receiver. For 
that reason the three-tube arrangement, shown further on, 
is preferable. 

There are four methods by which Major Armstrong 
succeeded in obtaining super-regeneration, but in the 
present case the results are accomplished by the simul¬ 
taneous variation of the positive and the negative resist- 


RADIO FOR EVERYBODY 


325 


ances of the circuit. This is realized by means of the 
second feed-back circuit (shown in the diagram under 
the numbers 13, 14, 15, 16) which is adjusted to oscillate 
at a lower frequency than the incoming signal. The 
proper phase relations between the negative and positive 
resistances are obtained by adjustment of the condensers 
13 and 16 and the coupling between the coils 14 and 15. 
According to Major Armstrong’s own data, for which 
the author is indebted to Mr. John Binns, Radio Editor 



The so-called “flivver” Armstrong super-regenerative receiver, 
making use of only one tube. 1.—Loop aerial, 12 turns on 3-foot 
frame, wound spirally. 2.—Secondary of usual vario-coupler, with 
twice usual number of turns. 3.—Primary of vario-coupler. 4.— 
Variable condenser, .001 micro-farad. 5.—“C” battery, 4 volts 
maximum. 6.—Vacuum tube, amplifier type. 7.—Resistances of 
12,000 ohms each. 8.—Variable condenser, .001 micro-farad. 9.— 
Iron core choke, 100 milhenries inductance. 10.—Telephones. 11.— 
Fixed condenser, .005 micro-farad. 12.—“B” battery, 80 volts. 
13.—Variable condenser, .0005 micro-farad. 14.—Duo-late***! •'oil. 
1,500 turns. 15.—Duo-lateral coil, 1,250 turns. 16.—Variable 

condenser, .005 micro-farad. 17.—Storage battery, 6 volts or 8 
volts, according to tube used. 18.—Rheostat. 


of the New York Tribune, it will be seen that the two 
large duo-lateral coils 14 and 15 must be in an inductive 
relationship to each other. It will be found that this rela- 




































326 


RADIO FOR EVERYBODY 


tionship is very critical, and the greatest possible care 
must be exercised in adjusting this relationship, as well as 
obtaining the correct amount of capacity in the two con¬ 
densers 13 and 16. 

Although these condensers are shown as variable in 
the diagram, they do not necessarily have to be of the 
regulation variable air condenser type. They can be 
made up of a number of fixed condensers connected in 
parallel with each other and so arranged to multi-point 
switches that any one of them can be brought into or taken 
out of the circuit. In other words, they can be variable 
in steps. 

The loop aerial can be constructed on a square frame 
three feet long on each of the four sides. The wire can 
be wound around this frame either in solenoid or spiral 
fashion. If the former, there should be ten turns, each 
spaced a quarter inch apart, and if in the latter form there 
should be twelve turns, each spaced a quarter inch apart. 
Number 18 cotton-covered bell wire can be used. The 
Armstrong super-regenerative set works best in connec¬ 
tion with a loop. It is essentially a loop set. 

The loop is connected across the primary of the vario- 
coupler, which is shown in the diagram as coils 3 and 2. 
respectively. The tuning to the wave length of the incom¬ 
ing signal is done by means of the condenser No. 4. The 
secondary of the vario-coupler should have about twice 
the number of turns it normally has when used for ordin¬ 
ary purposes. 

The grid battery shown in the diagram as No. 5 con¬ 
sists of two pocket flashlight cells joined in series, giving 
a potential of approximately 3 volts. The negative 
terminal of this small battery must be joined to the grid. 

The 12,000-ohm resistances and the 100 milli-henry iron 
core choke coil are standard instruments used for filter 
purposes in telephone repeater circuits, and they can be 
obtained from most radio shops. Condenser No. 8 can 
be built up of fixed units in the manner described for 
condensers 13 and 16. 


RADIO FOR EVERYBODY 


327 


In this particular circuit it must be remembered that 
there are seven critical adjustments to he made. This is 
the price that has to be paid for getting one vacuum tube 
to perform four separate and distinct functions success¬ 
fully. 

The 1 hree-tube Armstrong Super-regenerative 

Receiver 

It is an anomaly of radio that the three-tube Armstrong 
super-regenerative receiver should be far simpler to 
operate than the single-tube arrangement, but such is the 
case. This is due to the fact that in the three-tube ar¬ 
rangement the various functions are performed by in¬ 
dividual tubes and there is none of the fine adjustments 
called for in the single-tube receiver. 

Again the author is indebted to Mr. Jack Binns, Radio 
Editor of the New York Tribune, for the data which that 
journal received from Major Armstrong. In the diagram 
on page 329, note that coils shown as L-l and L-2 are 
composed of the primary and secondary of the regulation 
short-wave regenerative vario-coupler. The primary is 
L-l, but the secondary is used as the tickler coil L-2. 
In this case it may he necessary to add a few turns to 
the secondary in order to get the best results. 

The loop antenna is connected across the primary of 
the vario-coupler, and it should be tuned for reception 
at the usual broadcasting wave lengths. A three-foot loop 
will answer the purpose; hut where circumstances war¬ 
rant, a four-foot loop should be used. The loop can he 
tuned by having a clip connection that can he placed any¬ 
where along one of the outer turns. 

In the diagram only one rheostat is shown, but it is 
advisable to use a separate rheostat for everv tube. The 
coil L-3 shown between the detector and oscillating tubes 
is a duo-lateral coil of 1,250 turns. Any other form of 
inductance of the same equivalent value can be used in 
its place, but a duo-lateral coil is the handiest in form. 


328 


RADIO FOR EVERYBODY 


The values of the various condensers are shown in the 
diagram. 

Coil L-4 is an open-core choke coil with a total induct¬ 
ance of ten millihenries. Coil L -5 is another duo-lateral 
coil of 1,500 turns or its equivalent. 

It will be observed from the diagram that there is a 
filter system used in the circuit. This consists of the 
resistances R -1 and R-2 and the iron core choke coil L- 6, 
together with the condenser C-5. An audio-frequency 
transformer, marked T in the diagram, is placed before 
the final amplifying tube. 

The filaments of the three tubes can be lighted from 
the same storage battery. Major Armstrong made use of 
the Western Electric VT-2 tubes in his three-tube circuit 
here shown, requiring an 8-volt storage battery. It is 
preferable to use these tubes if they are obtainable, al¬ 
though Radiotron UV-202, which are 5-watt tubes, may 
be employed. Separate “B” batteries must be used, but 
if the diagram is carefully studied it will be noted that 
the “B” battery of the telephone circuit is led back to the 
first battery in order that a total of from 160 to 200 
volts is put on the plate circuit of the amplifying tube. 

The final detail of the circuit is the “C M batteries. 
These batteries are used for the purpose of putting a nega¬ 
tive bias on the grids of the tubes. They can be the high 
voltage “B” battery type, made variable. 

While simpler to operate than the single-tube super- 
regenerator, the adjustment of this circuit will be found 
somewhat confusing at first. When the circuit is prop¬ 
erly adjusted it gives forth clear and undistorted music 
and speech with tremendous volume. The only adjust¬ 
ment that is necessary, aside from tuning, is a slight 
change in the two variable condensers shown as C-l and 
C-3. 

It should be borne in mind that this system must be 
used with a loop aerial. If an outdoor antenna is at¬ 
tached to it the signals will be so strong that the vacuum 
tubes will be paralyzed. Another disadvantage in using 












































































































330 


RADIO FOR EVERYBODY 


an outdoor antenna is the fact that the set will radiate 
from the antenna and cause interference to nearby sets 
The Armstrong super-regenerative circuit is strictly a 
loop device, we again repeat. 

Numerous modifications of these two Armstrong super- 
regenerative circuits have been introduced. These have 
appeared in the various radio periodicals and in the radio 
section of the leading newspapers, to which the reader 
is referred. However, the outstanding modifications of the 
super-regenerative idea are covered in the matter which 
follows, covering the latest circuits: 

The Reinartz Circuit Reduced to Its Simplest 

Terms 

Of the many “trick” circuits lately introduced in radio 
reception, none has attracted more attention or has been 
championed with greater enthusiasm by its users than the 
Reinartz circuit, which makes use of a simple spider¬ 
web coil as its main feature. The Reinartz circuit has 
proved itself superior to the more elaborate vario-coupler 
and two variometer arrangement and to many other ar¬ 
rangements in common use. There are no critical adjust¬ 
ments for the plate or the grid circuits, and the set will 
oscillate well on any wave length to which the grid circuit 
is tuned, thus simplifying matters a great deal. 

As already stated, the main feature is a spider-web 
coil. In view of the fact that such a coil, already wound 
with the proper number of turns and provided with the 
correct taps, is available at any leading radio shop, it will 
hardly pay the experimenter or radio novice to make 
his own Reinartz tuner. However, if the reader wishes 
to make his own spider-web coil, the procedure is as fol¬ 
lows : 

Take a piece of % -inch bakelite, fibre or even card¬ 
board soaked in paraffin, and cut out a disk 5inches 
in diameter. Then cut eleven radial slots in the disk, 
spaced at equal distances apart, and each extending in 


RADIO FOR EVERYBODY 


331 


134 inches from the periphery of the disk. Eighty-five 
turns of No. 26 single-cotton-covered wire will have to 
be wound on this disk. First of all, the plate coil is 
wound so that it will come nearest the center or hub. 
It consists of 45 turns. The starting end of this plate 
coil goes to the lowest contact point on the tickler switch 
shown in our diagrammatic sketch. Taps, in the form of 
loops in the winding so as not to break the continuity of 
the wire, are taken ofif at every 15 turns and brought 
to their respective switch points of the tickler switch, the 
finishing end of the plate winding going to the antenna 
condenser. The method of winding the coil is to carry 
the wire up through the first slot, then skip a slot and 



The remarkably simple but very effective Keinartz receiver: A— 
Antenna. Cl—Ground. L-l, L-2, the outer turns of the winding 
on spider-web. L.-3, the plate coil on inner part of spider-web. 
C-l, 23-plate variable condenser. C-2, 11- or 13-plate variable 
condenser. GL., grid leak, variable, which may or may not be 
required, according to circumstances. GC—grid condenser, V 2 to 
2 megohms. FC—fixed condenser, .001. Dotted lines, L,.C., repre¬ 
sent where loading coil can he connected. T—telephones. 



















































332 


RADIO FOR EVERYBODY 


bring it down through the third, running along the other 
side of the disk so as to skip the next slot and coming 
through the fifth slot, and so on. One slot is skipped in 
every case. 

In winding the outer coil of 40 turns, the winding is 
divided into two sections although the wire is continuous. 
The starting end of the coil as well as the taps at the 2, 
4, 5, 6, 7, 8, and 9 turns are brought to an eight point 
primary switch, while a tap at the tenth turn is grounded 
through one plate of the secondary condenser. Then, 
continuing the winding of the outer coil, taps are taken 
off at the 26th, 33rd, 36th and 40th turns, the last being 
the end of the coil. 

The wiring connections are shown in the diagram on 
page 331. It will be noted that two variable condensers 
are used in conjunction with the spider-web coil, one a 
23-plate condenser of about .0005 micro-farad capacity, 
and the other a 11 or 13-plate condenser of .00025 micro¬ 
farad capacity. No grid leak is used, but the grid con¬ 
denser should be of .00025 micro-farad capacity. The 
“B” battery should be variable from 16 to 22V 2 volts. 

The dotted lines and arrows indicate the “tie-in” point 
for a loading coil, if the wave length range is to be in¬ 
creased. The set shown has a range of 150 meters to 
about 425 meters. 

The Bishop Ultra-regenerator 

With a view to obtaining a super-regenerative receiver 
without the mysteries usually involved in the Armstrong 
arrangement, there has been developed what is known as 
the Bishop Ultra-Regenerator. Here is a simple and in¬ 
expensive receiver which gives remarkable results, and 
is therefore well worth building by the radio novice of 
an ambitious turn of mind. 

The various parts of the Bishoo ultra-regenerator are 
shown in the hook-up on page 334, for which we are 
indebted to the Radio Globe which published full instruc- 


RADIO FOR EVERYBODY 


333 


tions for the construction of this receiver. The hook-up 
is almost self-explanatory, with the exception of a few 
words regarding L-l, which is a spider-web coil. To 
make this coil a disk is cut from 34-inch thick fiber or 
other suitable material, to form a circle 6 inches in 
diameter. Nine radial slots, each 34 inch wide, and com¬ 
ing down to within 134 inches of the center, should be 
cut in the disk. The coil is wound with 50 turns of 
No. 24 D. C. C. wire and taps are taken off at the 25th. 
30th, 35th, 40th and 50th turns. Holes can be punched or 
drilled in each one of the radial arms, near the periphery, 
to take a machine screw with copper washers and nut, 
so as to take the taps and make neat, positive connections 
with the leads to a switch, if desired. The beginning of 
the winding is fastened to a screw placed in the very 
center of the disk, or if no screws are used, it is held 
in place by passing it through two holes placed close 
together, or held tightly in a knife slit. The winding 
starts at any slot. The wire is kept tight at all times 
and should slip smoothly into place as the form is turned. 
After the first turn has been made the wire will con¬ 
tinually cross itself at every slot. This makes the whole 
coil self-supporting radially. As the 25th turn is reached 
the wire is brought up to the nearest terminal screw and 
looped around it, and the winding is continued without 
breaking the wire. Or if no screws are used, some suit¬ 
able way of making a lead, such as by twisting a loop so 
as not to break the wire, is employed. The winding con¬ 
tinues until fifty turns are in place. 

Otherwise, the Bishop arrangement is simple. The 
various values are given in the hook-up on next page, and 
the connections are clearly delineated. Care should be 
exercised to avoid running wires in the plate circuit near 
or parallel with grid wires, and to keep all connections 
fairly widely spaced. 

After connecting up such a set, the bulbs are lighted 
and the variometer and variable grid leak are adjusted 
until a soft whistle of very high frequency becomes ap- 


334 


RADIO FOR EVERYBODY 


parent. This sound is not the same as the familiar howl 
of a tube, and is not offensive to the ears. The set is 
positively not working correctly until this phenomenon 
occurs. The antenna condenser is then adjusted for music 
or signals, and the variometer is rotated simultaneously 
to keep the whistle at full strength. The proper procedure 


r 










J 


The Bishop ultra-regenerator: A and B, mica fixed condensers, 
.002 micro-farad. C, 12,000-ohm resistance, which may be made 
up of carbon rods so as to be variable. L.-3, duo-lateral coil, 
DL 400 or DL 1,200, the value not being critical. E, dry battery 
of 90 or 150 volts, since the greater the voltage the higher the 
amplification. Amplifier tubes, preferably Western Electric 
VT-2 or 216-A type, or Radiotrons UV-202, if possible, variable 
condenser, .0005 micro-farad, with vernier. II, .00025 micro-farad 
grid condenser, must be of mica construction. R, variable grid 
leak for best results. J, plain rheostat. L-l, 50-turn spider-web 
coil with four taps. L-2, variometer. 


is to tune as near the wave as possible with the large 
condenser, then adjust with the vernier until the loudest 
response is obtained. 











































RADIO FOR EVERYBODY 


335 


Only a short antenna need be used with this system. 
As little as twelve feet of antenna wire will give remark¬ 
able results. If an antenna of more than 25 feet is em¬ 
ployed, the ground lead should be disconnected, since the 
loud signals will then paralyze the system. 

The Flewelling Circuit—the Last Word in 
Super-regenerators 

Still more remarkable than the Bishop circuit is the 
new Flewelling circuit, which is also a super-regenerator. 
Radio authorities are agreed that this circuit is the simpl¬ 
est possible arrangement for obtaining super-regenerative 
results with a single tube. The Flewelling circuit gets 
along without the large inductances such as are found in 
the Armstrong circuits, and replaces these with fixed ca¬ 
pacities which are not at all critical as to values. The 
inductance of the telephone receivers has been em¬ 
ployed where an inductance is required in the plate circuit. 

As will be noted in the diagram on page 336, of the 
Flewelling circuit, two compact inductance coils, such as 
the honeycomb or duolateral type, are employed. These 
coils are of the L50 and L75 sizes, used with a double¬ 
coil mounting to vary the coupling between them. Be¬ 
cause of the necessity of very loose coupling, it is perhaps 
best to use a three-coil mounting, leaving the center mount 
empty. In this manner a much looser coupling is obtained. 
The various values for the different components are given 
with the diagram. 

Any type of tuning arrangement can be employed with 
the Flewelling circuit, depending on whether an antenna- 
ground arrangement is used or not. I he circuit works 
quite well with a loop. For nearby reception no ground 
or antenna is necessary. If a large antenna is used, no 
ground should be employed. If a ground is used, only 
a short antenna, of say 10 or 15 feet, should be used. 

And Back to Radio Frequency 

Whatever may be said of the merits of the various 
super-regenerators, their intricacies are not to be denied. 


336 


RADIO FOR EVERYBODY 


Hence many novices prefer to come back to the more 
conventional methods of long-distance reception involv¬ 
ing the well-known tuning circuits and the radio-frequency 
form of amplification, if not just plain audio-frequency 
which, after all, is the simplest of any. 

Many improvements have been brought about in radio¬ 
frequency amplification, so that today even the veriest 
novice can construct a radio-frequency amplifier with any 



One-tube super-regenerative circuit of the Flewelling type: C-3, 
C-4, C-5, each approximately .006 micro-farad, not critical. R-1, 
1 to lMs megohms, critical. R-2, Ms megohm, solid conductor 
can replace R-2 and C-5, using amplification. “B” battery, 18 
to 250 volts using UV-201 tube. L-2, 50-tura coil. L.-1, 75-turn 
coil. C-l, condenser .0005 micro-farad. C-2, .00025 micro-farad. 
Dotted leads, 1 and 2, used in various ways, such as with either 
antenna or ground alone, or one side of loop connected with one, 
leaving 2 free. Both sides of loop, connect to 1 and 2. 


one of the many radio-frequency transformers or coils 
now on the market. Radio-frequency amplification can 
make clearly audible a signal from a distant station which, 
without such amplification, is entirely inaudible. In a 
properly designed amplifier the use of radio-frequency 
amplification often improves considerably the ratio of 
signals to static or strays. Radio-frequency amplification 
alone will not, however, give a strong enough signal to 





























RADIO FOR EVERYBODY 337 

operate a loud-speaker; if a loud signal is desired, audio¬ 
frequency amplification should be used. 

Some experimenters prefer radio-frequency amplifica¬ 
tion to the super-regenerator or the regenerative receiver. 
It gives clearer signals, to be sure, but it requires more 
tubes. 

The simplest form of radio-frequency amplification is 
obtained through the use of radio-frequency transformers. 
These transformers have two primary and two secondary 
terminals and are connected between the various stages of 
amplification in the same general manner as audio-fre¬ 
quency transformers. The hook-up on page 339, shows 
how one stage of radio-frequency amplification and a 
detector may be connected, without the use of any stabiliz¬ 
ing control. For one and two stages of amplification no 
potentiometer or stabilizer control is necessary, unless the 
loop or the receiver used has too high an inductance. 
When three stages are employed, a potentiometer or sta¬ 
bilizer control should be introduced as in our hook-up 
on page 341. 

Radio-frequency amplification can be introduced in any 
standard receiving circuit, in connection with the usual 
antenna and ground, if-desired. Generally, when such an 
arrangement is used, the regenerative feature is eliminated, 
for the distortions introduced by regeneration can then 
be done away with. However, if the operator is quite 
skilled and does not mind the extra trouble, the regenera¬ 
tive control can still be used, in connection with radio¬ 
frequency amplification. As a general rule it is best to 
use radio-frequency amplification in connection with a 
loop, for it has a tendency to broaden out excessively the 
tuning of a set used with a large antenna, for the simple 
reason that it makes any set that more sensitive and there¬ 
fore more responsive to signals in tune and out of exact 
tune. With the loop antenna, on the other hand, the in¬ 
creased sensitiveness of the radio-frequency amplifier ar¬ 
rangement is somewhat counteracted by the directional 
effect of the loop antenna, which sorts out the desired 
stations from the undesired ones. 


338 


RADIO FOR EVERYBODY 


Ready-Made Radio-Frequency Amplifiers 

For those who prefer to purchase ready-made radio¬ 
frequency amplifiers, there are several, types now available, 
some as separate units and others incorporated in standard 
.receiving sets. These amplifiers have been in everyday 
use long enough to prove that they are entirely practicable 
and something more than a laboratory experiment; indeed, 
they are ev'en available for the novice. 

The author has had occasion to use an Amrad two- 
stage radio-frequency amplifier and finds it quite satis¬ 
factory both in connection with a standard receiving set, 
and with a loop. When used in the former manner it 
makes for very broad tuning, which is apt to give a little 
trouble when the air is full of broadcasting stations. But 
when working late at night, when the nearby stations have 
ceased operations, the Amrad amplifier enables the author 
to pick up long-distance stations which would be quite 
inaudible without it. In connection with a loop it works 
very well indeed. The usjial regenerative control may be 
used even with the amplifier, but the adjustment becomes 
quite fussy and considerable skill and trouble, not to men¬ 
tion patience, are required. Still, the main object of the 
radio-frequency amplifier is to get away from regeneration 
with the distortion which it entails. 

Another popular type of radio-frequency amplifier is 
the tuned radio-frequency amplifier developed by the 
Grebe organization, which gives equal amplification over 
its entire wave-length range of 150 to 3,000 meters. It 
is of the tuned coupled circuit type. It has a tuned grid 
circuit using a variable condenser and an inductance, with 
the inductance switch so arranged that either a loop or an 
antenna may be used. The plate circuit is tuned by means 
of another variable condenser and an output inductance 
which may be either the primary of the vario-coupler of 
the usual loose-coupled tuner, or a special inductance coil 
supplied with the amplifier, which may be placed in any 
location where it is in inductive relation to the secondary 
circuit of the usual tuner, of whatever type. The first 



♦ 










































340 


RADIO FOR EVERYBODY 


method, of using the primary of the two-circuit vario 
coupler as the output inductance, may be used on any 
standard tuner in which this primary circuit is not 
grounded to .the filament, but in the Grebe three-circuit 
tuners the primary is grounded and therefore this con¬ 
nection cannot be used. Accordingly, a set of four out¬ 
put inductance coils is provided, having wave length 



Tuned radio-frequency amplifier of the Grebe type, giving equal 
amplification from 150 to 3,000 meters. A, Antenna. G, Groan'd. 
VC-1, Variable condenser. L, Inductance with- taps and switch. 

K, Usual rheostat for amplifier tube. P, Potentiometer. VC-2, 

Variable condenser. 

ranges, respectively, of 150-400 meters, 250-800 meters, 
725-1600 meters, and 1500 to 3000 meters. By this 
method it is possible to make use of any type of tuner 
for the tuned circuit feeding into the detector. Thus this 
amplifier may be used with any receiver. 

The Reflex Circuit—or Making Tubes Do Double 

Duty 

The final subject to be dealt with in this chapter and 
in this edition of our book is the reflex, circuit, in which 
a tube is made to do double duty. Originally worked 
out by the French radio engineer, Marius Latour, who 
is best known as the designer of the large high-frequency 































Three-tube radio-frequency loop receiver: C-l, Variable condenser. A, Amplifier tube. C4, Fixed condenser. F, 
Potentiometer. R, Rheostats. T-l, Radio-frequency transformer. C-2, Grid condenser and grid leak. I), Detector 
tube. T-2, Audio-frequency transformer. A, Audio-frequency amplifier tube. C-3, fixed condenser. 



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342 


RADIO FOR EVERYBODY 


alternators used in the French high-powered stations as 
a counterpart of the Alexanderson machines over here, the 
reflex circuit has only lately attracted wide attention in 
radio broadcasting circles. 

In brief, the reflex circuit employs a given tube as a 
radio-frequency amplifier, and then, after passing the 
radio-frequency energy on to the detector to be rectified, 
the same tubes are used again for audio-frequency am¬ 
plification. Thus with three tubes, the last being a detector 
which is used but once, it becomes possible to have two 
stages of radio-frequency amplification and two stages 
of audio-frequency amplification, getting the results nor¬ 
mally calling for five tubes. 

There are various methods of reflexing, but only the 
more typical ones can be dealt with here. A cryi?tal de¬ 
tector is often employed instead of a vacuum tube, be¬ 
cause of its simplicity and because it rectifies the radio¬ 
frequency energy, which is now so powerful as to be 
equivalent to signals from a nearby radio transmitter, more 
faithfully than the vacuum tube detector. The extraneous 
noises and much of the distortion in the usual receiving 
set is due to the detector tube. 

The diagram on page 344, shows a simple single-circuit 
tuner with a single amplifier tube used for radio-frequency 
and audio-frequency amplification, in company with a 
crystal detector. The connections are given and the parts 
indicated. It is highly important that the leads be made 
as short and direct as possible. The parts should be 
placed with this in mind. If possible, a UV-201-A tube 
should be employed, as it works very well and is worth 
the additional cost. 

The same general arrangement is used with a more 
elaborate tuner. To operate the set the detector is ad¬ 
justed so that the fine wire presses on the crystal. The 
tube is then turned up slowly until a loud response is 
obtained in the telephones, usually a howl or rumble. This 
noise may be stopped by adjusting the potentiometer. 
Then the condenser is adjusted until the broadcasting pro- 


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REFLEX AMPLIFIER DETECTOR 





























































































344 


RADIO FOR EVERYBODY 


gram is picked up. The crystal is then adjusted for 
maximum signal strength, followed by a readjustment of 
the condenser and the potentiometer. 

The diagram on page 343, shows a typical multi-tube re¬ 
flex circuit in which three tubes are made to serve as fol¬ 
lows : The first two' tubes are reflex amplifiers, serving 
as two stages of radio-frequency amplification and two 
stages of audio-frequency amplification. The third tube 






Keflex receiver using single vacuum tube and crystal detector: 
A. Antenna. VC, Series antenna variable condenser. L, Tuning 
inductance. G, Ground. AFT, Audio-frequency transformer, with 
I* lor primary and S for secondary. C-l, fixed condenser. P, 
Potentiometer. R, Rheostat. C-2, Fixed condenser.' KFT, Radio 
frequency transformer. I), Crystal detector. C-3, fixed condenser. 


serves solely as a detector. If desired a tickler coil may 
be placed as shown by the dotted lines to make the set 
regenerative as well. Hard tubes, such as the UV-201, 
must be used for the reflex tubes, while a soft or detector 
tube is used as the detector. 



































RADIO FOR EVERYBODY 


345 


The Wave Trap for Preventing Spark Interference 

So much for the various ingenious . circuits that have 
been developed of late. There is still space available here 
to say a few words regarding the wave trap, which is a 
simple device for eliminating spark interference. Many 
radio “fans” are annoyed by the interference from spark 
transmitters, and are unable to tune out the dot-dash 
signals. This is especially true in the case of plain single¬ 
circuit tuners which tune rather poorly. 

There is a good old stand-by to fall back on, in this 
case, known as the wave trap or filter circuit. It can be 



Details of a wave trap or simple filter circuit: R, Variable con¬ 
denser. S, Single point switch. 15, 25 or 50-turn inductance, de¬ 
pending on wave length range desired. 


constructed by anyone at a cost of less than $5.00, and 
will generally prove most helpful in eliminating spark 
interference. The function of this device, which makes 
use of a condenser and a winding in parallel with each 
other and in series with the usual tuner and the antenna, 













346 


RADIO FOR EVERYBODY 


is to trap the undesired signals and prevent them from 
reaching the detector. The arrangement shown in the ac¬ 
companying diagram consists of a variable condenser of 
.0005 micro-farad capacity or about 23-plate size, and a 
honeycomb coil or duo-lateral coil of 25 turns. If desired, 
one can make one’s own coil by winding 25 turns of No. 22 
double-cotton-covered wire on a cardboard tube 3 inches 
in diameter. R represents the condenser, B the inductance 
or coil, Y a shorting switch, which enables the operator 
to throw out the wave trap when it is not desired. 

The operation of the wave trap is quite simple. When 
spark signals are troublesome, the switch of the wave 
trap is opened and the variable condenser is adjusted until 
the spark signals are eliminated in whole or in part, de¬ 
pending on the effectiveness of the wave trap in this par¬ 
ticular. The primary circuit of the usual tuner may have 
to be adjusted because of the wave trap. 

If a trap is desired for 600-meter reception, the same 
arrangement is employed but a honeycomb or duo-lateral 
coil is used, together with .a variable condenser of 43-plate 
or .0001 micro-farad capacity. 


INDEX 


“A” Battery .121,154 

Abbreviations, Code . 171 

Aerial for Receiving . 94 

Aerial, Insulating the . 97 

Aerial, Loop Type . 107 

Aerial, Plain . 211 

Aerial, Purpose of . 13 

Aerials, Transmitting . 212 

Aerials, Types of . 100 

Aerial Wire . 95 

“America” Tests . 272 

American World-Wide Radio . 263 

Amplification, How to Improve . 315 

Amplifiers and Line Telephone . 178 

Amplifiers, Radio and Audio . 182 

Amplifying Apparatus . 177 

Amplifier Tubes . 127 

Antenna, Construction of . 276 

Antenna, Insulating the . 97 

Antenna Lead . 150 

Antenna, Loop .,..107, 153 

Antenna, Purpose of . 13 

Antenna, Receiving . 94 

Antenna, Types of . 100 

Antenna Wire, Kinds of . 95 

Antennae, Improvised . 150 

Arlington Time Signals . 86 

Armstrong Regenerative Circuits . 138 

Armstrong Regenerative Sets. 141 

Armstrong Super-Regenerative Circuit . 323 

Audio Frequency, Meaning of . 182 

Audio Frequency Transformers . 179 

Avalon-Los Angeles Radio Link . 56 

Battery, “A” . 121 

“B” Batteries . 157 

Batteries, “B” or Plate . 121, 157 

Battery, Filament . 121 

Battery, Plate .*. 121 

Beat ;Notes . 140 

Bed Spring Antenna . 150 

Biasing the Grid . 315 











































348 


INDEX 


Bishop Ultra-Regenerator. 332 

British Imperial Radio Chain . 261 

Broadcasting, Cost of . 67 

Broadcasting, Government . 69 

Broadcasting Stations, Class B. 66 

Broadcasting Stations, Department Stores . 64 

Broadcasting Stations, Kinds, . 63 

Broadcasting Stations, Newspaper . 64 

Broadcasting, Toll . 65 

Broadcasting, What Is . 39 

Buzzer Test . 145 


“C” Battery. 315 

Call Letters . 176 

Capacity, Meaning of . 12 

Church Services, Radio . 59 

Circuit, Armstrong Super-Regenerative . 323 

Circuit, Bishop Ultra-Regenerative . 332 

Circuit, Flewelling Super-Regenerative . 335 

Circuits, Primary and Secondary .>. 129 

Circuit, Reflex . 340 

Circuit, Reinartz . 330 

Class B Stations. 66 

Classes of Radio Licenses . 172 

Code, Abbreviations ./. 171 

Code, Continental and Morse . 164 

Code, Learning the . 166 

Code, Practice Set for . 166 

Coils, Duo-Lateral and Honeycomb . 131 

Coils, Inductance . 131 

Coils, Spider-Web . 133 

Compass, Radio . 252 

Condenser, Antenna Series . 146 

Condensers, Transmitting . 220 

Condenser, Variable . 116 

Construction of Simple Receiving Set . 275 

Continental Code . 164 

Continuous Waves . 207 

Continuous Waves, Meaning of . 100 

Continuous Waves, Reception of .140,163 

Continuous Wave Transmitter . 229 

Cost of Broadcasting . 67 

Counterpoise . 104 

Crop Reports . 74 

Crystal (Detector . HO 

Crystal Detector, Testing the . 144 

Crystal Receivers . U 2 

CW Transmitter . 230 

















































INDEX 349 

Damped and Undamped Waves . 9 

Damped Waves . .****’” ‘ ’. 207 

Definitions, Radio . ~24 

DeForest Vacuum Tubes DV-1 and DV-6317 

Department Stores and Radio .. . . . . . . . . . . 64 

Detector, Crystal . HO 

Detector, Sensitiveness of Crystal . 144 

Districts, Radio .’. 174 

Donle Tube . 320 

Dry Battery Tubes . 303 

Dry Battery Tubes, DeForest DV-1 . 317 

Duo-Lateral Coils . 131 

DV-1 and DV-6 Vacuum Tubes . 317 

Electro-Dynamic Telephone . 196 

Farmers’ Service . 73 

Filament Battery . 121 

Fire-Escape Antenna . 152 

Flewelling Circuit . 335 

Frequency of Radio Waves . 4 

Frequencies, Spark . 207 

German World-Wide Radio . 261 

Government Broadcasting . 69 

Ground . 13 

Ground, Arrangement of . 276 

Ground, How to Make a . 102 

Guided Wireless . 254 

Head Sets . 133 

High Speed Radio . 270 

History of Radio Telephone . 44 

Honeycomb Coils . 131 

Horns, Improvised Loud-Speaker . 192 

Hydrometer. 154 

Indoor Antenna . 150 

Inductance Coils . 131 

Inductance, Meaning of . 11 

Inductance, Spider Web . 133 

Installing Receiving Set . 149 

Insulating Aerial or Antenna . 97 

Interference, Prevention with Wave Trap . 345 

Jack, Multiple. 158 

Jack, Plain . 158 

Laws, Radio . 174 

Licenses, Classes of Station . 172 













































350 


INDEX 





Licenses, Operator’s and Station . DO 

Licenses, When and Where to Get . 170 

Lightning, Protection from ......105,276 

Lightning Switch . 10s 

Loop Aerial with Radio Frequency . 541 

Loop Antenna .107, 153 

Loop, Construction of . 326 

Loose-Coupler . 130 

Loose-Coupler, How to Construct . 288 

Loop with Armstrong Super-Regenerative Circuit . 324 

Loud-Speakers . 191 


Market News, Radio .. • • • 73 

Morse Code . 164 

Multiple Jack .*. 158 


Newspaper Broadcasting Stations . 64 

Operating a Receiving Set . 143 

Operating the Regenerative Set . 160 

Operator’s License . 170 


Plain Aerial Transmitter . 211 

Plate Battery . 121 

Plug, Telephone . 158 

Potentiometer, Use of . 315 

Practice Set for Mastering Code . 166 

Primary and Secondary Circuits . 129 

Principles of Receiving . 17 

Principles of Sending . 15 

Principles of Transmitting . 15 

Principles, Radio . 3 


Radio, American World-Wide . 263 

Radio, British Imperial Chain . 261 

Radio Broadcasting, Beginning of . 58 

Radio Central . 266 

Radio Compass . 252 

Radio Communication Laws . 174 

Radio Communication, Principles of . 14 

Radio Control . 248 

Radio Definitions . 24 

Radio Districts . 174 

Radio-Frequency Amplification . 335 

Radio Frequency Amplifiers . 185 

Radio Frequency, Meaning of . 182 

Radio Frequency with Loop Aerial . 341 

Radio, German World-Wide. 261 

Radio Inspector . 174 














































INDEX 


351 


Radio Link .50,272 

Radio Frequency Transformers . ’ 186 

Radio Licenses . 170 

Radio Market News . 73 

Radio-Phone Broadcasting . 1 . 39 

Radio Principles . 3 

Radio Telegraphy, Use for Market Reports . 84 

Radio Telephone Transmitter . 229 

Radio Frequency, Tuned Type . 340 

Radio Telephony, Early Days of . 44 

Radio Time Signals . 86 

Radio, Trans-Atlantic . 268 

Radio, Unusual Uses of . 247 

Radio Waves . 4 

Radio Weather Bulletin . 87 

Radio Wiring Symbols . 25 

Radio, World-Wide Chain . 259 

Receiver, Armstrong Super-Regenerative . 323 

Receiver, Bishop LIltra-Regenerative . 332 

Receiver, Flewelling Super-Regenerative . 335 

Receivers, Crystal . 112 

Receivers, Radio-Frequency . 335 

Receiver, Reflex Type . 340 

Receivers, Regenerative . 141 

Receiver, Reinartz . 330 

Receivers, Telephone .133, 195 

Receiving Aerial . 94 

Receiving Continuous Waves . 140 

Receiving Equipment . 93 

Receiving, Principles of . 17 

Receiving Sets, Dry Cell Tube . 306 

Receiving Set, How to Construct a . 275 

Receiving Set, Installing the . 149 

Receiving Sets, Kinds and Prices . 21 

Receiving Set, Simplest Type of . Ill 

Receiving Sets, Simple Vacuum Tube . 159 

Receiving Set, Single Circuit Regenerative . 309 

Receiving Set, Vacuum Tube Type . 288 

Receiving Undamped Waves . 140 

Reception of Continuous or Undamped Waves. 163 

Reception of Spark Signals . 162 

Reception, Regenerative . 138 

Rechargers . 157 

Reflex Receiver . 340 

Regenerative Sets, Operation of . 160 

Regenerative Receiver, Construction of .294,307 

Regenerative Receiving . 138 

Regenerative Receiving Sets . 141 

• 


















































352 INDEX 

Reinartz Circuit . 330 

Remote Control by Radio . 248 

Reports, Crop and Market . 73 

Santa Catalina Radio Link . 54 

Secondary and Primary Circuits . 129 

Sending, Principles of. 15 

Series Condenser . 146 

Shielding . 142 

Shields .. 142 

Signals, Time. 86 

Single Circuit Regenerative Set . 309 

Spark Frequencies . 207 

Spark Gap, Action of . 207 

Spark Gaps . 224 

Spark Signals, Reception of . 162 

Spark Transmitters . 209 

Speed of Radio Waves . 4 

Spider-Web Coils . 133 

Station License . 170 

Storage Battery Rechargers . 157 

Storage Battery, Testing the . 154 

Super-Regenerative Circuit, Armstrong . 323 

Symbols, Radio . 25 

Telephone, Amplifier for .. 178 

Telephone and Radio . 54 

Telephones, Electro-Dynamic . 196 

Telephone Plugs and Jacks . 158 

Telephone Receivers . 133,195 

Telephoning to Sea . 54 

Terms, Radio . 24 

Test, Buzzer . 145 

Testing Crystal Detector . 144 

Testing Storage Battery . 154 

Toll Broadcasting Station . 65 

Tickler. 139 

Tikker . 140 

Time Signals . 86 

Traffic Capacity of Radio . 272 

Train of Waves . 206 

Trans-Atlantic Stations. 268 

Transformers, Audio Frequency . 179 

Transformers, Radio Frequency. 186 

Transmitters, Action of . 206 

Transmitters, Radio Telephone . 229 

Transmitters, Types of. 195 

Transmitters, Continuous Wave . 229 
















































INDEX 


353 


Transmitter, CW and ICW . 230 

Transmitters, Simple . 209 

Transmitters, Spark . 209 

Transmitters, Tuning the . 216 

Transmitting Aerials . 212 

Transmitting Apparatus . 195 

Transmitting Condensers . 220 

Transmitting, Principles of . 15 

Tubes, Detector and Amplifier UV-200 and 201. 125 

Tubes, 'Donle.318, 320 

Tubes, DV-1 and DV-6 DeForest . 317 

Tubes, Future Developments in . 322 

Tubes, UV-201-A . 312 

Tubes, Operation on Lighting Current ;. 322 

Tubes, VT-1 and VT-2 . 318 

Tubes, Western Electric . 318 

Tuckerton Station. 268 

Tuning Coil. 113 

Tuning Devices, Tuning Coil . 113 

Tuning Devices, Variable Condenser . 116 

Tuning iDevices, Variometer . 113 

Tuning, Meaning of. 7 

Tuning the Transmitter . 216 

Types of Aerials or Antennae . 100 

Types of Vacuum Tubes . 125 

LTndamped and Damped Waves . 9 

Undamped Waves, Reception of . 163 

Undamped or Continuous Waves . 207 

Undamped Wave Reception . 140 

U. S. Bureau of Markets and Crop Estimates . 73 

Unusual Uses of Radio . 247 

UV-201-A Vacuum Tube . 312 

Vacuum Gap Lightning Protector . 106 

Vacuum Tubes . 153 

Vacuum Tube Amplifiers . 177 

Vacuum Tubes, Donle . 320 

Vacuum Tubes, Future Developments in .,. 322 

Vacuum Tubes, Operation on Lighting Current . 322 

Vacuum Tube, Principles of . 118 

Vacuum. Tube Receiving Sets . 159 

Vacuum Tube Receiver, How to Construct . 288 

Vacuum Tubes, DeForest . 317 

Vacuum Tubes, Types of . 125 

Vacuum Tube, UV-201-A . 312 

Vacuum Tubes, VT-1 and \ 1 -2 .,. 318 

Vacuum Tubes, WD-11 . 303 
















































354 


INDEX 


Vacuum Tubes, Western Electric . 318 

Variable Condenser..■. 116 

Variable Condenser, How to Construct .. 290 

Vario-Coupler . 130 

Variometer. 113 

Variometer, Construction of . 298 

VT-1 and VT-2 Tubes . 318 

Waves, Frequency of Radio . 4 

Wave Length . 7 

Waves, Radio . 4 

Waves, Speed of Radio . 4 

Waves, Train of . 206 

Wave Trap . 345 

WD-11 Tube . 303 

Weather Bulletin . 87 

Western Electric Tubes .,. 318 

Wind Numerals . 88 

Wind Reports . 88 

Wire for Aerial . 95 

Wired Wireless . 254 
















































































































































































































































































































